It’s entirely possible to do something like that - the same way it was in 2008. Keep that shit separate.
You have to let users say “fuck off, Nazi.”
You have to find moderators who’ll see that and say “yeah, fuck off, Nazi.”
The site itself doesn’t need to do much of anything. Reddit’s smartest feature was the separation of communities, so people could largely ignore shit they didn’t want to deal with, and all the admins forbade was starting shit across communities. That way tiny subforums of decent people could be reasonably protected from interference by bastards, and tiny subforums of bastards could be kept irrelevant.
For example, the /r/Holocaust subreddit was run by and for Holocaust deniers, for years. Obviously that’s awful. But it affected approximately nobody, beyond the initial unpleasant surprise. There wasn’t some “trending” feature that fed unwitting users to Engagemagog, whenever people spoke negatively of the fuckers responsible. Early reddit was a site with Nazis, but very plainly not a site by or for Nazis. Decent people outnumber them by a huge margin. So long as they can safely spot, exclude, and tell off those bastards, the co-existence of bastards is tolerable.
Where deliberate neo-Nazi forums like Voat differ from that is in explicitly protecting the worst among them. They screech about freedom of expression but only ever mean the unquestioned ability to yell at the outgroup. That’s why none of them really like deliberate neo-Nazi forums. They can’t stand each other, either. They demand a captive audience of victims.
If people lack the freedom of association to stay the hell away from Nazis, your site exists to supply bigots with victims.
If people lack the freedom of expression to even tell Nazis to fuck off, your site exists to deliver those victims on a silver plate.
It is possible to hit a balance where intolerant bastards are tolerated, but treated in accordance with their beliefs by everyone sensible and kind. But it’s much simpler and easier to recognize that some beliefs aren’t worth protecting.
Also that article is predictably a mix of good insight and total crap. SSC has the worst double-reverse-zero-awareness both-sides-ism on the internet. ‘Fox lies and projects, but I dunno, maybe they were okay at some point. And as the right lost touch with reality, The Media™ really did develop a liberal bias, proving them right somehow.’ Nah. Identifying bullshit is not a bias. People getting more disgusted as assholes embraced fascism is not somehow to blame for people embracing fascism. If consistent human decency looks like “ghettoization” against Nazis, your perspective is fucked beyond all reason.