I can only speculate on what was in his mind.
The mere fact that he went on Brown's show indicates that he was not expecting to get nailed on his criminal record -- not on CNN and not by Aaron Brown. That's why it was so easy for them to sucker punch him.
Ritter has an exalted opinion of himself and is much better known that his co-author, who is probably not recognized by anybody who hasn't seen the book. Ritter probably thought, with some justification, that Brown would be professional enough to separate the two of them and not hold the co-author's behavior against him. As a major anti-America shill for the left, he understandably expected CNN to treat him like visiting royalty. But with what we now know about Ritter's reality testing, it's not surprising that he didn't see any of this coming. He's an extremely loose cannon.
He was NOT sandbagged.
Perhaps you should watch; as I said: 1:37 AM EST.