Re: Problem student!!
Have you tried to "be harmonious" with the guy in class and "talk to him off the mat"?
The guy may not be a problem in the bigger picture even if he is a training challenge for the dojo's students. Doesn't sound like he's actually hurting anyone. If sensei is a good sensei and he knows about the problem, and he isn't doing anything about the problem, perhaps he does not see it as a problem.