He is not liked by all but Bill Maher is quite an unique individual.
It's weird, I don't like Maher at all, but I do watch his show pretty regularly.
He usually gets on some pretty good, interesting guests--and though I disagree with a lot of what Maher says (or more how he says, and to the extremes he takes them), he's not scared to take a conversation in a direction that a lot of people wouldn't--so I do enjoy his frankness.
But Maher is just not as smart as he thinks he is (nor is he funny), and when he is wrong on something, he won't concede. He was clearly wrong on this topic, and all 3 members of his panel were explaining how different his situation was from what was going on with Ingrham, but he kept hammering on.
This is something that I find very annoying with comedians these days. They confuse freedom of speech with freedom from consequences. You CAN say whatever the fuck you want, but you can't go cry about bullying or unfairness if people don't like what you said. If you say something offensive, people have a right to be offended.
Don't like it? Don't be a dick.