Good question...except that it's not perfectly fine when Maher says it (or worse).
However, you're no doubt referring to the level of "public outrage" and/or "media huff". Just thought of something: Rush is a heavyweight (no pun intended), while Bill M. is (as Sarah Palin terms him) a mere "mosquito". If a mosquito sucks a few drops of your lifeblood, no big; that's what mosquitoes do.
Or something like that.