Fortunately, we don't tend to see him there very often (this was the first time I have seen him at GGA, actually). Unfortunately, every time I have run into him he has tried to sell me drugs, or in the case of last Friday, a 40.
I'm not sure exactly how to handle this situation. I don't think that his presence is majorly detrimental, but it's definitely annoying. I like being able to leave my stick in the room and not having to worry about someone mashing around on it in ST like it's an American cabinet. I wish there was a way I could lock my setup into a certain set of games without having to remove every other game I have stored on it. Last week my setup became a Divekick setup, which confused me a bit.
I would say we wait and see if this becomes a consistent issue before anyone tries to take action.
Alternatively, we could all switch to Hitbox layouts and never have to worry about it.