If it wasn't spelled out in his contract, those promises, well, I'm sure you know how they go. He is goofy but it seems to work for him. But if it's a turn off to that audience they want to keep, then he would have to make changes or pass on it.
At one time Colbert was a total turn-off for me. Now I like him. It took me a bit to get him. He would definitely have to ease up on his politics. But if he's willing to do it, he would do really well. He's got the charisma.
I'd be open to checking out some others.