Whether Google like it or not, being in the media business (and Google News is a media outlet) requires some transparency on their part. Steve Rubel points to the problem:

Google is getting smacked for removing conservative e-zines and blogs from Google News. To date, Google has done a poor job of explaining why certain blogs are enshrined and others aren't. They need to publish some standards around who they are willing to include and why.

What content they are pulling isn't nearly so relevant as why it's being pulled. Like a newspaper, they have no requirement to publish anything they don't want to publish; it's their site, and they can do what they want. If, on the other hand, they want to retain actual credibility, they need to explain what standards they use for including (and not including) content.