The question assumes the possible beliefs of the person you are putatively protecting as if it were facts. If he’s riding a subway train and is obviously Jewish, he’s working class, so might vote Republican and love Trump, especially if he self-identifies as a Zionist. No need to defend him, unless he’s too feeble to defend himself.
Lastly, the best defense against a masked “protestor” is to rip off the mask, point and laugh at him, and kick him lightly in the a@@ while he flounders about for directions from his inner fuhrer. Do that just once, and it will catch on. No need to go to jail or kill anyone. Mockery defeats fascism.
I’m talking about when it reaches the point when Jews are being beaten, and worse, in public places. Maybe it won’t get to that point. 4 more years of a democrat president and the odds get a lot better that it will. 1930s Germany becomes a more likely proposition in that scenario.
To these people a Jew is a Zionist. If you look like a Jew you then must be one. Rip off the mask and laugh? Tell that to the guy getting stomped by a group of thugs.