"say something" and then what? Convince them that being a nazi is bad so they leave? Let's be real here, the only realistic way of dealing with a nazi at a protest is through physical force.
>I also didn't call the anti vax protestors Nazis. I said they were okay with Nazism, while similar it is different
1. the wording is from the parent post, not you
2. Does this change much? Would you call that bus/subway full of people as being "okay with Nazism"?
>I definitely would not want to be associated with Nazis but maybe that's just me
Clearly the organizers doesn't want to be associated with nazis either, but as mentioned above, my suspicion is that unless you're with a group of left wing activists, the chance that there's someone willing to use violence to stop the nazi is fairly low.
Incidentally most leftist groups try to keep good relations with the police, even when doing civil disobedience. I’ve seen a large group block traffic, and only those union members who planned to get arrested did so, slowly and quietly.