I think that Jim Cramer thought that Jon Stewart would play nice (since Stewart is known to do that even when his opponents from the Bush administration came on his show). So Cramer was hoping that people would see the two patch things up and hopefully that would solve his image problem. But unfortunately Jon didn't play nice and took the gloves off. So I think in the end Jim Cramer's gamble of showing up on the show hurt him rather than helped him. Those clips Jon showed really proved Jim Cramer to be a liar.
So in the end, I think Jim Cramer made a mistake of showing up.