"This Legal Tactic Can Keep Nazis Out Of Your City"

This sounds legit, at a glance--that is to say: it doesn't sound to me like an obvious violation of either First or Second Amendment rights. And, off the top of my head, I'd think that the state has a legitimate interest in preventing the formation of private armies.
   Though as usual, I want to add: bad people have Constitutional rights, too. If there's a legitimate way to keep crazy protesters from being armed, I'm for it. But until I hear what somebody like Volokh has to say on this, I have to remain a bit skeptical, what with not in any way being a lawyer and all... And I'm not sure it's permissible for cities to strive to keep away protesters on the basis of the content of their views. Sounds not to me, actually.
   And: if we would reign in Antifa, a lot of these problems would go away. Seems to me that C'ville was pretty typical: I think C'ville thought it'd just let Antifa do its thuggy thing, and that would constitute another incentive for the wingnuts to leave. And that's why the cops hung back. Antifa typically initiates the violence. (Though the tiki-torch mob apparently started it at the Jefferson Statue the night before. And good on those student for defending the statue with force.) As long as Antifa is allowed to openly use violence to deny right-of-center groups their right to assemble, those groups will have good reason to come armed and ready for violence.
   And, of course: without the counter-protesters last year, Unite the Right comes and goes without incident. Needless to say, left-wing kooks have the same right to assemble that right-wing kooks have--but there's nothing preventing cities from telling them that they have to have rallies in different places. (So far as I know, anyway.)