I don't get why you made this argument and then immediately rebutted it in the next paragraph. If people with enough power dislike a group of people enough, in this case white nationalists, they can be marginalized to the point they're making TOR websites.
The idea that censoring free speech isn't a problem because people can just start their own website is about as naive as free speech absolutism is. It trivializes censorship. If a major platform banned all lgbt discussion on the pretense it was no big deal because peoole could start their own website nobody would have any of it despite the fact that the only thing that had changed is the target.
Realistically censorship haalways been part of the internet and human society more broadly, it's an inevitability. The broad issues I'm concerned with is concentration of power over speech and increasing echo chambers in online communities. Reddit has shifted more and more towards central control including implicit threats for moderators/communities who step out of line.