Everything is getting recorded nowadays.
Very few people actually want to go through with punching someone for any reason.
Someone is recorded chanting nazi bullshit and telling people they're a nazi, don't defend them.
Once people stop saying they're nazis, then we can worry about it getting used to justify shit, perhaps?
Our experience with police body cameras would suggest functional recordings of events are more discretionary than we would like, and the mob rarely cares to thoroughly validate evidence. So long as they have a recording of someone saying the word "nazi", well, then, on we go -- and many, many people want people hurt who are unwilling to do it themselves but more than willing to gin up any mob that falls readily to hand.
And by the time people stop saying they're Nazis it will be far too late to stop. All the people I mentioned who want to punch people and get away with it will vociferously agree on one thing: only a Nazi would ever want to make it harder or less popular to punch Nazis. Or rather, they'll punch first to defend their golden ticket and someone will come up with that later.
We've tried this before, you know. We've tried making it okay to kill witches and list Communists working in the State Department and throw suspected Japanese secret agents into internment camps. Every single time we've tried to single out a group as acceptable targets
in extremis for a limited duration and with all the due process we can afford, everyone stops listening after "acceptable targets" and is running down the road, torches and pitchforks in hand, and all the definitions have twisted and broadened and fuzzed one punch at a time. Every single time, it's become a way to settle grudges and censor the opposition and let our basest impulses rule.