See I don't think Chris or Sonichu or whatever is misgendering. Chris has kind of a unique view among troons where he just accepts that he used to be a different person years ago and is just completely comfortable with it. Even when he's reminded that "Classic Chris" was based and straight pilled he just gets mad at Classic Chris like he's just a different person all together. I'd imagine "Teen Chris" is the same way. So of course referring to him as a he makes sense. Teen Chris is a boy.
I know this perspective is brought on by his weird way of looking at shit and his dimensional merge crap, but in a way Chris comes off as a lot more self assured and stable than most troons out there.