Short of mass murder, there is not much else that could have been to done to legitimize white supremacist and steel the resolve of their followers. Key point being "their followers". The people that were on toeing the line on joining or financial supporting these groups are getting a push over the line, because Antifa and BLM played right into their rhetoric. They know they are hated, they don't need broad appeal, just a narrow sliver of the population that they need to appeal too.
The leaders of these groups are laughing all the way to the bank. They couldn't have hoped for a better outcome and all the idiots that think they are "counter protesting" are getting played and helping their cause.