I don't think that's entirely fair.
On The Rewatchables, he clearly sees himself as the moderator who's job it is to make the discussion more accessible/casual when his guests, who are usually Sean Fennessey and Chris Ryan, start to get too into the weeds about "filmmaking." He knows he doesn't know as much as those guys do, and he doesn't care to. He's fine being the voice of the lowest-common-denominator because he knows his guests will talk about themes, film history, shot framing, historical significance, etc...His job is to make sure it stays grounded and loose. And to his credit, I think he sometimes (not always) says shit because he knows it will tweak SF and/or CR and make for some enlivened discussion, precisely because the dynamic of friends busting balls is at the center of his aesthetic. He's not a moron, even if he sometimes says moronic things or goes off half-cocked. And I've never gotten the impression he's ever actually been chuffed by anything his guests say.
I think the closest analogue is probably Adam Sandler. Sandler basically plays the same guy in every movie (with some exceptions) which is a version of "Adam Sandler." He's been doing it for so long that I think people assume he's really like that all the time, and while I'm sure he is to a certain extent, I'm also certain that Adam Sandler in a business meeting, or Adam Sandler at home with his wife, is not the same guy that you see on screen. He knows that in most of his movies, people expect the Adam Sandler 'tude, the Adam Sandler comebacks, the Adam Sandler shtick. Likewise, I'm pretty sure Simmons is deliberately playing his "Bill Simmons Sportsguy" role, at least to a certain extent, on these podcasts. It's easy, he has fun, and it's what his fans have come to expect.