Good question. Past experience has shown us that the DM has to jump through hoops to just barely keep the campaign on life support if the Foot in Mouth guy tries to correct his own problems in game.
My main question, though, from above was what course of action would my cleric - a preacher of peace - take if he was saddled with a guy that is going to constantly challenge and/or offend NPCs. We can't talk to him out of game, as we have done it many, many times in the past to no avail (well, he has gone from a train wreck of a role player to only a major pileup on the interstate...)
