Mainstream for millennials and gen z - maybe even gen X. He’s probably not mainstream for boomers.

Because your definition of mainstream is incredibly narrow. In the age of the Internet, mostly boomers and some gen X are watching TV. I don’t watch what’s on any tv anywhere. I haven’t used TV in the traditional sense in over a decade and that’s very common in my demographic. To me - those “news” networks spread as much disinformation as Joe Rogan does. (Which is to say - a lot and practically all the time)