A soulless shell can act only on command, even what can be called instinctive actions are more like “body memory” and a given “program of actions” of the one who gave the command. This creature can't feel anything at all. If you lift up old bones with necromancy and command a skeleton to stand guard, the skeleton will carry out the program you have given it, but the real person (soul) - the one to whom this body once belonged - is at that moment in the domain of their deity, living their afterlife there and they are not affected at all.
Oh look, we even have an example of that in the game. As if Astarion's zombie ending wasn't ghastly enough.
How come the game doesn't chastise us for making this choice?
