I've read and heard Rush's comment from Sunday several times. The only thing wrong he did was make an un-PC comment in a PC-dominated forum.
The way I read Rush's comment, he's making a criticism on the media as much as on McNabb. He's saying that certain elements of the media play up McNabb as being better than he actually is. He didn't say McNabb isn't talented or deserving to be in the NFL, just that he's not at the level that some put him to be. I'm not a huge football fan, so I'm not one to say how talented McNabb is.
Rush is a commentator, and he's paid to give his opinion. He did so, and lost his ESPN job because of it.
Still, Rush may end up making the wrong group angry. If the Oxycontin allegations turn out to be true, I bet a large number of his fans will turn on him.