I've brought this up before when it comes to companions in WOTR but I don't know why some of them probably most of them stay if they disagree with your choices. That part is unbelievable to me unless they're brainwashed.
Seelah leaves on one of the evil paths but not another. Daeran says he doesn't like the extreme good or evil forgot his actual words. But he doesn't mind staying.
It is a "now or never" situation in a fight against world threatening demons, so most companions reason its a end justify the means situation unless you go completely against their believes.
