Jon Stewart never decided to represent a certain side of politics, that's just where people put him. He absolutely hates it when people want him to carry a banner. I remember him telling stories in an interview, about how people would come up to him after the show, and say something like "I think you're very funny, and I've always loved the show, but you made a joke about global warming, and that's too serious to joke about. I'm never watching the show again". Jon is obviously flabbergasted at this.
I also recall his recent complaints about not being able to joke about Obama. At one point, he made a joke about him, and the audience responded so negatively, that Jon commented that they were allowed to laugh at Obama.
The most frustrated I remember him being with the audience was when he implied that the Democratic party was as charismatic in this country as Hamas. The crowd booed a little, and as he turned to do the next bit, he said "would you just fucking accept it?!", and then continued.
Anyway, I still think he's very funny, and apparently a good chunk of the country agrees, especially if they're around my age(this isn't a common occurence).