Depends on the context, and how serious and violent the Nazi. If they're just an isolated idiot who isn't politically active and isn't stupid or thick-headed enough to actually follow through on their claimed beliefs, then violence isn't really justified. They're an idiot, but not a threat. The problem is with anymore more dedicated or crazy than that. Past that point, you immediately get to people who want to murder or enslave hundreds of millions. Thats not hyperbolic, that's literally the goal of Nazi beliefs, and a logical extention of almost every belief that stems out of it or is adjacent to it. In theory, yes, it'd be nice to be able to talk down people like this, or use existing systems of power to force them to places where there isn't a risk of them trying to murder or enslave people, but unfortunately, when you're talking about groups who don't respect human lives, the law, or anyone but their designated, arbitrary in-group, then those aren't always viable means. This is esspecially true if that person is already in a potition of power. Basically, if someone wants to kill you, you can't always wait for them to successfully aquire the means to do so before acting. This isn't hyperbole or metaphor, this is literally what we're talking about here. The problem is in drawing a line of who is an actual threat, and if there are other means to "disarm" them.