Completely agree. Though I think the issue here is bigger than that. Journalism by its nature is subjective. So it may be bias, and that's still crummy, but at least the people consuming it know what they're getting.
Facebook, on the other hand, portrays its "trending" news as being determined objectively based on what people are sharing. That goes beyond bias to manipulative. It would be the same if Google were filtering conservative news sites out of its results.