Why did Imus get fired for saying "Nappy Headed Ho's" and nothing has happened to Bill Maher?

Bill Maher stated "I thought when we elected a black president, we were going to get a BLACK president. I want him in a meeting with the BP CEOs, you know, where he lifts up his shirt where you can see the gun in his pants. That's — 'we've got a motherfu**ing problem here?' Shoot somebody in the foot." HOW IS THAT NOT RACIST?!?!? So only a black president would pull a gun? Only a black president would use the words "we've got a motherfu**ing problem here?" If this isn't racist then I don't know what is. He might as well have said "When I voted for a black president I wanted a n****r that would bust a cap in someone's ***!"