Godwin’s Law isn’t a law as much as an observation.
It’s the observation that when one or both sides are resorting to literally the most inflammatory insults they can think of, the discussion is over and it’s now just a shouting match. He just used “Nazis” as a convenient example of a group which was, in his mind, universally loathed in his social context. In other contexts, it could be “gays” or “Christians” or “Muslims” or “cishets” or any other identifiable category.
The group doesn’t matter. The intense vitriol matters.