Gay men who are "bears" present as very traditionally masculine, normally with beards and dad bods. That's pretty much all there is to it.

I could easily see why a gay teenager raised with certain stereotypes would be confused about being gay. If he expected the gay world to be all about effeminate men (as he might expect given certain media portrayal) then learning that other paradigms exist might be quite helpful and even reassuring.

Firing a teacher over the issue seems ridiculous, explainable by nothing but homophobia.