Except they're not "mouth pieces". Local journalists are much more independent than national ones. This instance by Sinclair of attempting to combat the national news broadcasters was a David vs Goliath attempt, and they are coming out of it much worse than David did.
"Independence" is incompatible with "being forced by corporate to grant your credibilty to their talking points".
You can't say Sinclair is "combating the national news broadcasters"; they themselves are a national news broadcaster. They just happen to like branding themselves with local faces.
Please explain how "independent" they are, in the context of them being forced to repeat a script from Sinclair news. I'm not even sure how you can miss the contradiction.