I don't think there really needs to be a penalty decay or anything like that. You should have gotten the message the first couple of times. It's not hard to be a decent human being, follow the game rules, or hold back base urges to act unreasonably.

I suppose I don't agree with any victimless/untargeted profanity complaints because the filter exists as an option for the "victims," but on the other hand, so many people can't spell well enough that they'll be unintentionally bypassing the filter anyway.