I think the difference in our thinking is that I believe that morality is objective, independent of any entity's thoughts or point of view, while you seem, to me, to be implying that morality is subjective, depending entirely on the perspective of the relevant parties.
I'm not entirely sure what you're arguing exactly, but by the same reasoning I could conclude that to Adolf Hitler, the Jews and the Allies were Demons and that the Nazis were Angels. I would hold that Hitler's perspective on himself is irrelevant by virtue of the people he harmed, and that the same holds true for Epic despots like Steelheart or Regalia.