The left wants to be in sole possession of the broadcast media, and of public discourse. The passive population of this country has unwittingly allowed them to get ever closer to that goal.
You didn't watch and listen to enough of the interview, or objectively enough. If you seek out the entire interview and watch and listen carefully, he is not singling out Fox News as being opinion news . . . he's describing the industry in general. Not surprisingly, that includes just as many "news" sources on your side of the political spectrum as on mine, if not more.