That's the fantasy they have, that the MSM is conservatively biased. I don't think they actually believe it. They just float it out there to see if anyone will bite. Eric Alterman spews this garbage all the time and even has a "what liberal bias?" website.
I was talking to one of my best friends the other day. My friend hates Republicans and was on a rant blaming Bush and Republicans for every imaginable problem under the sun. I mentioned that he feels that way because all the news he hears and reads is mostly from liberal Big Media. He screamed at me "what about Fox News?" When I got done laughing, I told him that Fox is watched by only a tiny percentage of the viewing public.Big Media still draws the lions's share and much more of the viewing audience. He quickly changed the subject.
People like my friend truly believe simply because there is ONE! network that isn't liberal, the media is balanced in it's coverage. In fact conservative messages only get a tiny percentage of the market. We have a long haul ahead of us. Fox, talk radio, and the internet are just starts.