My point would be that by it's nature, regardless of content, NPR appeals to a different set of listeners than Fox News does. The useful comparison would be between NPR and talk radio, which seems easy: there's a lot of conservative talk radio.
I don’t understand what you mean by saying that NPR appeals to different group of listeners “regardless of content”, especially as you later observe existence of conservative talk radio. NPR and conservative talk radio appeal to different groups of listeners, but what else make it so, other than the content? Similarly, what makes Fox News appeal to non-whites more than NPR, other than the content?
Maybe! If you think conservative talk radio has more diverse appeal than Fox News, that's an argument. I'm just bristling at comparing NPR to cable news of any sort.