it was a sort of open secret in hindsight.
the biggest proof would be the whole "Meet the Sess" episode from X-Play that was basically based on the idea that Sessler got his own talk show ala Dennis Miller to rant about video games. The bulk of the episode was Morgan auditioning different X-Play characters (including Johnny Xtreme and Sessler's IRL brother, who had a reoccurring bit where everyone fawned over him because he was more attractive than Adam) to replace Sessler and the final segment was a "preview" of the talk show which gave us a glimpse at the cunt behind the "awe shucks self-effacing nerd persona" Sessler disguised himself on X-Play.
in hindsight, it was a sign that Sessler was a cunt and that if given free reign to do a show he'd be ranting and raving and insulting his audience and any guests who held an opinion he didn't agree with.