"Super" PCs

[Geigan]

Well, he did say literally in the OP.

I feel that in such a case, steps need to be taken to explain to him that just going around raping everything is not what the DM (and hopefully everyone else involved) wanted when they said they were going to run an evil game and to stop or he'll have to leave the group completely because that's just messed up and transmits unpleasant and unsavory things about himself as a person that no one really wants to know.

I agree and apologize for assuming. If it's literally, then I think that steps need to be taken to stop it, if the group is uncomfortable with it. An Uber-NPC won't stop undesirable behavior, he needs to talk to him and make it clear with the backing of the rest of the group that that is unacceptable.