Labelling yourself a Nazi is confessing to conspiracy to commit genocide. This is a crime, whereas being disloyal to the president is explicitly not a crime.

I'm not a fan of vigilante justice in general, but at least the targets in the "punch a nazi" case have confessed, and the punishment called for isn't death.

However, I do not believe that posting "punch a nazi" is a conservative enough position given that the standard of evidence for labelling someone a nazi, in practice, is that they disagree with you on the internet.