There are numerous other holes in the logic other then the ones I mentioned in the linked thread, FWIW. I'd have to get a few days off where all I could do is replay the game and pay attention to the lines and codexes in detail, but I don't have that luxury.
Thx for your answer 
So, you think it was a mix of selfish and strategic reasons? Personally, I think Loghain is the type of person who would have sacrificed (very reluctantly) his own daughter if he was sure that it was in Ferelden's best interests. Luckily for him, her daughter and him seemed to share the same views on politics (or, at least, she could not bring herself to contradict him), which put her in a safe position in this context.
Still, the description you give of Lhogain's behaviour gives me the impression that he was in a dictator mindset. Also maybe the aliance with Orlais would have turned to be a good thing for Ferelden, and for Orlais too. Celene seems to be a progressive, pragmatic but fair ruler, nothing to suggest that she would have treated Ferelden badly.
Anora had to support her father in the beginning. At this point in time, there's a war going on and Loghain is the best-equipped to lead the armies. But Loghain's insistence on doing everything himself puts her in a precarious situation. She could oppose him in public, undoubtedly, but it would mean giving the Bannorn even more reason to fight against Loghain and would actually lead to more chaos, which is something she's trying to avoid.
Loghain also had the full backing of his own forces along with the greater part of the Coastlands thanks to Howe throwing in with him. That automatically gives him the edge. By throwing her lot in with him, her hope is that the (at this point in time) leaderless Bannorn will not try and fight against a man who they have no chance of winning against.
Alas, Teagan's statements and Loghain's statements incited the Bannorn. Both are at fault for the tension in the political spectrum, but it seems that the fault for the first blow goes to the Bannorn (it wouldn't make sense for a man who wants to avoid Civil War actually go and strike the first blow).
Indeed, you hear tales of how the Banns can't even unite against Loghain. They're either fighting for Loghain, against Loghain, against themselves, etc. Most of the time they get their asses handed to them, but in the off chance they do win against him (like when 3 banns united) their victory is short-lived as it leaves them without sufficient defenses to go against the Darkspawn.
Is Loghain a dictator? Well, yes and no. You have to understand the political situation he's in. His direct act of demanding the Banns unite under his banner does fly straight in the face of Fereldan custom as pertains to the freeholders, but it's also done in the name of ensuring Ferelden appear strong and not fall to petty infighting after the loss of their king. Anora is no doubt named the queen during that Landsmeet (as she's consistently referred to as such, so she must've secured th) but she's not a Theirin, which would rustle a lot of jimmies.
In the absence of a Theirin heir, it opens up a political vacuum. Many would seek to fill it, and this would lead to a chaotic civil war. Loghain fills the vacuum immediately, hoping to quell any and all hopes opportunistic nobles might have, and demands their support in defeating the Darkspawn. He cites them as the immediate concern then and there, though he makes it a point to mention offhand how others would take advantage of their weakened state (Orlais, which is right when you look at the history of the nation).
He declares himself Anora's Regent. Anora herself is fine with this (again, she has to be). In truth though, this was perhaps one thing Loghain shouldn't have done. He says he did everything to protect Anora from the fallout that might occur, when Anora doesn't need to be coddled. She could handle the politics on her own. Indeed, talking to him about Anora and saying he knows her better then anyone will yield a "You think so? I'm not so sure of that".
I like to think Howe kept Loghain from going to Anora for advice by trying to manipulate him into believing Anora unfit for rule due to grief from Cailan's death. Think Grima Wormtongue. And when Anora brings up Cailan, Howe then goes somewhere off-screen to Loghain "See my liege? She is unfit for the burden of rule. Come to me for help." and Loghain fell for it hook, line, and sinker. Certainly, Gaider said Loghain thought himself above Howe's influence but Howe was manipulating Loghain.
Anyway, the civil war was the result of a few things. Loghain's demands reminding a once-oppressed nation of their Orlesian overlords' similar things (though the reasons are different), Teagan inciting the banns, etc. As the banns fought against the Regency, they were effectively committing treason against the crown.
When the civil war broke out, grudges were brought to a boil. Old grudges from centuries ago. The thing is, once a civil war occurs it's next to impossible to get it to go back to normal. You'd need sufficient power brokers to stop it, people who can effectively sway people to their side. This is, in effect, Eamon and Anora at the time of the game with the absence of Bryce. Teagan's next, and we can't forget the Warden. I'm talking strictly politics here, which Loghain has no mind for.
As a result of this, with Teagan deadset to be against Loghain, Loghain had to turn his attention towards quelling the rebel banns. This is the prudent course of action from his perspective. Stepping down would have been pointless once the banns started fighting against one another (remember, these are the people who would go to war over a tree). You can't fight a war on multiple fronts, not easily anyway. And the banns, although hardly united, would still present a credible threat to Loghain's efforts to dealing with the Darkspawn.
They could attack his supply caravans or harass his troops. Geographically, the banns stand in the way for his southern movements. Even passing through his own territory wouldn't solve the problem, as he'd eventually come into conflict with banns who aren't on his side. And even then, the troops he does have at his disposal aren't enough to deal with the Darkspawn. That's why he needed the banns to resupply the army.
Fighting the rebel banns was the thing that needed to be done once they elected to start a war out of a sense of short-sighted altruism and "honor". These are the people who are supposed to be protecting their lands from foreign aggressors, yet they saw fit to attack a man who wanted to deal with the Darkspawn. How many lives did these banns throw to the flames?
Sadly, his alliance with Howe presented its own problems. Howe began to embezzle from the royal treasury and committed numerous acts Loghain had no knowledge of and never approved of while he (Loghain) was out in the field leading his armies -- for instance, the needless Purge of the Alienage. Coupled with the Civil War, Howe's actions led to the treasury becoming near bankrupt. This isn't the first time the nation suffered a near-bankruptcy. When Maric disappeared, Loghain exhausted a great deal of funds trying to find him.
Loghain had previously turned to the Circle of Magi for help against the Darkspawn, as they were Ferelden's greatest possible asset against them. He nearly had them on his side too, though Wynne's meddling in matters she's ignorant of and Uldred's ****** reaction ended up keeping them away from Loghain. Still, had he gotten them, he would have had access to the Formari and the Lucrosians and could have had them help keep the treasury running.
But he didn't. And so Howe offered him a "solution". To sell Elves to a bunch of Tevinter Magisters to fund the war-chest. Ignoring for the moment how this is a rather shoddy way to portray the struggles of Elves because it's only really used in relation to Loghain as either a means to get you to side against him or Alistair for his drama, it was a "dirty fix".
Now I'm not saying I discount it. Rather I just think it should've been retooled a bit to actually have a great deal of focus on the implications and consequences of such an action, rather then being a simple emotional crutch (unless you're a Tabris, in which you faced that stuff a lot). Leaving it at that from a writing perspective doesn't do much for me, particularly when everyone uses Ostagar as being the definitive "anti-Loghain" statement (in-game and out). If anything, it's the slavery, as it can mark him as being no better then the Orlesians, even if his reasons aren't like theirs (where it was For The Evulz).
But anyway, that's tangential, and the slavery thing is certainly something to hold against him. But, and I only say this for the full exploration of it all, the Alienage is presented to us as an indefensible location. True or not in the grand scheme of things (it's arguable to me, given how it's walled off yet it's also got a lot of dilapidated hovels) it's certainly true in the context of it only being able to be saved because the Warden will make a heroic rescue.
Beyond that, talking to Loghain yields further insight. At the time of the Warden's intervention, approximately 36 Elves ("a few dozen" as he says) were sent out with the Tevinters and the war-chest was 1/3 of the way full. There's no real way for us to determine the amount of coin a slave in Thedas would go for, and Hayder's statement in DAII of how Castillon's slaves -- originally refugees trying to flee the Blight -- were worth 100 sovereigns a head seems outlandish. At a reluctant guess, I'd put a slave as being perhaps anywhere from 40-60 sovereigns, and that's being generous.
But anyway, with the war chest completely filled, Loghain's intention was to resupply the army and then, once that was done, supply the Elves so they could defend themselves.
Is his logic a bit warped? Certainly. He thinks that by this time even being alive as a slave is preferable to dying without hope at the hands of the Darkspawn. Whether one agrees it's better to live as a slave or die without hope is up to them, though a case could be made you're dead either way. The only difference being how literal it is.
Still, Elves being able to defend themselves would've been great and falls in line with the original Loghain that led an entire group of Elves in the rebellion.
Am I defending the slavery? Not really. I just think examining the full context of it is important, but I agree it's one thing that can be used to justify his execution. Other things... not so much.
As for Celene... well... let me link to a post of mine with what I said on that topic recently.
(I can elaborate later if people wish).