Could you find the exact Heaven's Feel quote about that? Unlimited Codes usually provides an abridged but otherwise accurate portrayals of the characters, and in it, Kotomine says: "perform the evils that you must"
Again, before you make fun of me for posting the Unlimited Codes video, post the Heaven's Feel one, if it can gainsay this one (and tell me the time stamp because I know that it's probably going to be a long video). Oh, yes, at around 28:31 is that statement in full detail in Heaven's Feel: