Well, liberals and Democrats always claim to be more interested than conservatives and Republicans. You'd think they would lead by example in who gets on the air and make sure the staff is diverse.
Part of the problem is that leftists see "diversity" as an end in itself - except when it comes to diversity of opinion, of course.
Walter Williams doesn't sub for Rush Limbaugh just because he's black, he subs because he's an intelligent, articulate, and well-educated individual of a compatible political persuasion who has a euphonious radio voice.
Who gets on the air is who can attract listeners and sell advertising. Who gets on the staff is who's capable of doing the job right and well.
Content of their character, and all that jazz.