Do you know any of those boys who were kind enough to make him turn off the rap song? If so, you might ask them if this kid really is a bigot or he’s just being a jerk. If he’s a jerk, it would be worth talking to the father. If he really believes that crap, then I’m not sure approaching the father would make much difference.
I know one — and, more importantly, I know his parents.
Great idea.