They attack O'Reilly because he illustrates how far left the government media organs have gone. As Chris Matthews said they cover both sides... "Left vs. center-left, for it or against it, there are all points. Same with CNN. But there is another network, Fox, where there's absolutely no debate. It's just trashed every single thing."
For these loons there is opinions that matter except theirs. It doesn't matter that nobody is listening to them.