Jon could absolutely destroy anyone on a debate stage. Mainly because it's a popularity contest, and he's spent his entire life learning to be popular on screen and stage. He's also a smart guy with great insight into a lot of situations.
None of that means he would be a good president. It's a different set of skills.
The bottom line though, would he be better than the alternative? And I hear what you're saying. Those nazi crack monkey's put on a hell of a show, how could Jon possibly do a better job? I'm not sure, but given the option, I think I'd give him a shot.
He softballs when he wants to get more guests. If he goes after every politician, they all run and hide. To see him actually debate you have to see him off his own show. He's given very compelling addresses to congress as well.
And seriously, he's one of the most popular TV personalities in the country. What you're saying is you don't like Taylor Swift's music, so she must be a shitty entertainer. Maybe you're just not the target audience?