But casting him as an intellectual and a history buff? Have they ever even watched his program?
I wouldn't jump to conclusions about Beck as a person just based on how he acts on his program. It's fairly plausible that he hams it up a bit to play the 'everyman who loves his country' role that he's carved out. I haven't watched his program, but from what I hear it's a bit more over the top in comparison to his show back on CNN. He could very well be an intellectual and history buff, who happens to become an emotional demagogue once he's in front of the camera. Stewart and Colbert (as you noted) aren't the only ones playing up the entertainment angle.
"Paul Lynde to block..." -- a contestant on "Hollywood Squares"