As for the others on your list, non-alt-right people (cf. non-alt-right sites) might be more inclined to discuss (cf. host discussions about) these "facts" if their primary use wasn't to be woven into otherwise fictional narratives claiming to be coherent justifications of racism and homophobia.
So, the same thing mainstream society has been doing for the last 6 years, just for different races and groups?
If they criticized things like Outreachy (which literally discriminates people based on race and gender [1]) with the same energy that they criticize the "alt-right" then I would believe them. Otherwise it's just hypocrisy.
The challenge is that when they come into conflict, we know that humans tend to discard the facts before the world views.
There are also plenty of things that can't be discussed in alt-right places, only in proper free-speech places (which are rare and often heavily contaminated with alt-right due to them being kicked out of everywhere else). E.g. if you wanted to discuss whether "consensual child molestation" is actually harmful you'd get banned from any right-wing space.