In reality, the rest of the bar laughs at and mocks the one Nazi and he probably stops coming or at least shuts up, even though he hasn't been banned. This is how most non-/pol/ generals have handled it, and it works. It's how plenty of real bars across America handle it too, when the bar and patrons earnestly subscribe to free speech as a aspirational principle for guiding human behavior, not limited to simply the first ammendment binding the hands of government. If somebody wants to reveal themselves to be a dumbass, that's entertainment for everybody else.