The inside-the-law approach that works to some limited extent is public community rejection. Things like large groups showing up and standing with their back to the Nazis.
The method that has historically stopped Nazis like this involves getting some level of police cooperation and beating them up
Loudly ask why mass shootings happen to decent people instead of these scum. Play videos of the bombing of Dresden and the executions after the Nurnburg trials to remind them about what we do to Nazi fuckheads.
Legally I want the government to do nothing to suppress free speech. I recommend individuals to be a little extra.
Flying lead keeps Nazis under cover while you douse them in gasoline.
Shoot most of them and recruit the rest to NASA. Oh wait…
Styrofoam dissolved in gasoline works well
