What you want is a world in which Nazis are irrelevant but in which they aren't punished for existing. What you call a "genuine system of justice" does not punish people like Spencer simply for being alive and holding racist views. And if it's your belief that those people shouldn't be attacked, then that's fine. But then you have to accept the consequences of that approach, which is that people like Spencer will have a platform and they will remain relevant when a few people inevitably decide to punch them and we act like it's this crazy spectacle.
The fallacy here is assuming that the only way to attack and fight against people like Richard Spencer is to punch them when you see them. At what point in my argument did I say do absolutely nothing at all against fascism? (Hint: I never said that, because I do not remotely think that).
No, what I want is a world in which the punishment for the horrible stuff you think is not an instant assassination hit squad like what you're advocating. You literally think that we should allow people to instigate physical violence without anything approaching a court of law. We don't even advocate the police being allowed to do that, never mind every citizen on the streets.
Like what is this, Judge Dredd? Instant execution? No, I don't think so.