Well i literally playthroughed whole game to a BG veteran friend of mine and that was his way of playing.(I was giving attributes and doing gameplay while he was doing dialogue and story choices. I haven't given any spoilers not even hints about story part):
Riordan wants you and Alistair to recruit Loghain and Alistair whines a lot just to interrupt him.(Ser Whines A lot?)
So you literally have no idea what's going on except that Riordin's words like "GW can recruit anyone, we're not judges"
"Sure" you'd say, after all Riordan is your senior and seems to know a few things more than you and Alistair. He tries hard to tell you something. Must have a good reason since he was being tortured by Howe just an hour ago.
And Anora says "Either you gain a general or he dies and you will take your revenge"
"Fine, why not?" Either you gain +1 warden, a former war hero, a strategical genius, a highly respected man at least by common folk... Or you get revenge.(Even being GW is a curse, so even if he joins your order he'll die soon enough but i'll pass this)
So he went with "Let's recruit Loghain" option and totally disappointed by Alistair's leaving. Thought : "He had an oath. Archdemon coming. He was a nice fellow but why he turned into a cry baby? Haven't Daveth was more questionable than a general? He was a canditate so why a war hero can't be? Just because Alistair wants to see color of his blood?"
So we reloaded. And this time even he wanted to see reason, he couldn't agree with that "wah wah pedal" called Alistair. Wouldn't suit his roleplaying and wouldn't make sense to kill someone just that some companion wanted him to do so.
That's where he quit playing.
So in short Loghain should live to make sense. That non-logical choice between Alistair vs Loghain(while one leaving) just placed there to make things "critical". But instead of being a "hard choice" it is simply annoying, ridiculus and leaves a sour taste.
Landsmeet's beginning is usually where i quit playing my characters aswell. No matter how i was a "manipulator", how high was my approval with Alistair, how i talked like "We need everyone we can get" before and at Landsmeet cancels it all and drops my character into mess. Since i can't RP what's the point of RPG anyway?
TLDR: Let Loghain live, anyone disagrees dangers the mission because of their prefers and put their own "hatred" above whole country. Or be female noble and kill him just to sit on throne, but don't lecture me about how bad and ambitious Loghain was 