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It really means "People who's ancestors were Jewish but the current generation is probably 2 or 3 generations removed from that". They are no more Jewish than any random stranger in the street. And it's representative of nothing at all.
Antisemites come in all flavors. They often trot out "Jews" and people with Jewish sounding names to bolster their case, as if saying "Here are some Jews who hate Jews, who better to prove that it's true?" I happen to know a third generation Baptist named Elliot Goldberg.