If I had to make a guess I'd say about 75% legit 25% shtick. I think they generally believe the ideals they're talking about and things they're saying, while exaggerating or going over the top with guesses and questions for an entertainment purpose rather than honest belief of it
"I am appalled that somebody who is the nominee...would take that kind of position"
"A court took away a presidency"
"...the brother of a man running for president was the governor of the state..."
It's horrifying because Trump is blunt instead of making overt implications.
Anyway, it's no surprise that he's going to say that two of the most popular radio show hosts, don't believe what they say. I'd be shocked if he said anything good about them.
Catawa is my favorite bleeding heart liberal.