If you believe that Facebook is something more than a toy, then it seems reasonable that they'd have freedom of expression, press, speech, so on. As such, if people choose to get their news from Facebook, it's no different than them getting their news from Reuters, FOX, the New York Times, or Bloomberg. Surely you wouldn't imply any of them wouldn't have editorial control.

Comment sections on news outlets can remove whatever they want, I don't see why it'd be any different for Facebook, if you genuinely consider them a news outlet.