I agree that Nazi views are reprehensible and that the guy probably deserved to get punched, but this sort of vigilante behavior makes me uneasy. It's just going to enable more vigilantism, and escalate the rate and severity of these attacks.
These guys do deserve to be told to shut the fuck up, and they deserve to be locked up if they attack people. But these things should be done within the confines of the law. Going around the law to fight against Nazis is not the way to do it.
You bet that Nazis right now are using this incident to justify more violence. That'll lead more people to seek violent confrontations against Nazis. On and on and on.
The escalation is in response to neo-nazis themselves escalating. Motherfucker was out in public wearing armbands and harassing people. We had Charlottesville just over a month ago. Neo-nazis are becoming more bold and brazen every god damn day. If anti-fascists DON'T escalate in response, then we all risk getting trampled. There is no other scenario.