Still, puncturing one's innocence, particularly in a world literally built for war, is never something to be celebrated. Worse, Sizemore isn't just learning that he has power, he's learning that he is, in fact, bred to
kill and kill well, not just dig tunnels and make crap golems.
He
hates killing, and every time he has to end another life it kills him a bit more inside. Sure, he's a
Technical Pacifist but being forced to confront that pretty much all he does is kill is just going to turn him into a
Shell Shocked Senior which is not the fate I'd wish on anyone.
Heck, considering the structure of the game, it probably would have been a kindness for Sizemore to die before he had to order his creation to smoosh the heads of two lovers. The longer he lives the more lives he must take, and
it's not a taste he enjoys.