No, my argument is for the greater good. If the end result is better than the present then it's justifiable. People call him evil because of their own selfish morals. Morals are flexible and as such are situational. Just because you think something is morally wrong does not make it so.

Also, you mean "Vol. 12 & 13". I've read them multiple times. It was Demi's plan and actions to commit those cruel acts. Ainz had no real idea of what was going on. Demi always gives him a rough idea of his plans or actions but never great details. A great example is the "two legged sheep". However, Demi only does those basic explanations because he believes Ainz' knows (which we know he doesn't).