but instead I think I've just made myself out to be a science denier

Because you literally are denying science.

And what indicates he's a chud? The fact that he's on a different instance?

And it's not pedantic or a "redditor comment", it's a dude sharing a cool fact he thought others would like.

Shit like this is part of why autistic people have trouble socializing. We just wanna share cool facts and you act like we're being assholes for it and use that as an excuse to be assholes in return.