See my post below responding to cheeks. Society accepts offensive language on certain formats, not others. There's no way Maher could have gotten away with what he said in the middle of the day on AM radio.
Anybody can drop HBO at anytime they want. HBO obviously isn't very scared or they would have dropped him.
With Limbaugh, thousands of American companies pitch their products DURING his show. Now those companies are getting heat to stop supporting his show. This isn't surprising. Maher has no corporations supporting his show, so he doesn't have to worry about them witholding their support.
Also, I believe liberal radio host Ed Shultz got suspended from his show (and from MSNBC) when he said offensive things about Laura Ingram. I guess you forgot that?