The Proud Boys aren't racists.Once again trump has denounced white supremacists.
But he also denounced the proud boys for some reason, i don't agree with him on that.
However their clashes with Antifa and BLM have not painted them in a great light. They are a little too violence-prone and have started a few scuffles themselves. Useful if we actually get to the point of wide scale civil conflict, less useful in avoiding reaching that point to begin with.
I'm not sure how much Trump knew about them before the debate; he may have got a briefing afterward that changed his view on them.