I don't think Joe is a racist, but frequently he puts his foot in his mouth when he's trying to be funny. The problem he has here is he is talking with an Indian American about the support he gets from that community, and tells him "You can't walk into a 7-11 or a Dunkin Donuts without a slight Indian accent". This kind of thing is fine for the Simpsons, but he was running for President at the time.