Now you're twisting what I posted. Where did you get "much kinder fate" from? I said: "Selling them means they're just as dead, but it leaves him better able to act", as in, the coin he gets for selling them is of more use fighting the darkspawn than the Elves themselves would be. If you're twisting things to this extent, I see no reason to continue this discussion.
To be fair, Loghain does use the argument "What's worse, to die without hope or live as a slave?" IIRC.
Or perhaps that's me not remembering the Loghain dialogues correctly. Persephone's got them memorized though so if I'm wrong she can set me straight 
That said, there are a lot of other things brought up that must be taken into consideration, some you mentioned Callidus. First the Civil War the Bannorn started and Howe's embezzling, coupled with the lack of Lucrosians/Formari on his side, made it necessary to Loghain. Second, Loghain tells you that he would've supplied the remaining Elves once the army was fully supplied (the Warden stopped it when a few dozen Elves were shipped off and this brought the treasury back to 1/3 of its needed strength)
Not saying I excuse it or justify it. I merely explain the rationale behind it. And while I hold him accountable from an ethical/moral standpoint, I do understand a lot of what drove it to occur.
It's.... weird for me, how I feel about it. It's a crime I hold against him, but the situation that drove it to occur isn't his doing alone. Plus I think it was more Howe's idea then Loghain's. Loghain just signed off on it (which still makes him culpable)
Though I would say that the Wardens probably would've done the same thing. Hell, we very much can do the same thing and let Caladrius take the slaves with him.
There were 4 legions of Chevaliers at the border, twice as many as at the River Dane, not just 200 soldiers.
NVM Orlais' history with occupying countries they just wanted to "help" defend against the Blight.
Of course Riordan gives us a larger number (that makes no feasible sense and shows BW's ineptitude at writing, but it's still a different and larger number) -- two dozen divisions of cavalry.
Also, worth pointing out Celene admits she wanted to take control of Ferelden. The reason? Exactly what Loghain says about peace during RtO. Fighting someone else's war.