I think it's really interesting you assume the player is in a negative state of emotion...I would not assume that. I would assume they're playing the character some way they can justify (hence the IC route of consequences.)

I agree with your last paragraph, which is exactly why I made the post (and what I think you'll find my suggestions for response entail.) If you think an email to the imps isn't formal enough, I disagree...anything more formal would probably make imps burn-out 5x faster. And, again, I don't think a game mechanic free consequence like a title should be keeping anybody up at night (or burn IMP hours.)

A counter discussion...

There's an evil character that appears to either be roleplaying an extreme evil persona or being a total jackass of a player as a pattern (pick one...spam killing, full sac/looting, etc.) Their actions are not against the rules, but impacting the culture of the game with their extreme tactics. Would you have us...

a) Do nothing
b) Warn the playerbase via a title/reputation as described above in an IC capacity
c) Take measure to "harm" the character's mechanic's by removing skills/abilities