I think this phenomenon is hugely interesting. There's a fairly vicious strain of anti-semitism running through the Left-wing Protestant churches as well. I had a run-in a few years ago with a Baptist minister at Boston University who insisted that Israel's targeted killings of racist terrorist war criminals was "barbaric", and proceeded to give me a lecture about how his ancestors were slaves, lynched, etc. The obvious implication being that Israel was racist. I noted that this was a bit ironic considering the fact that it was quite clear that, in his opinion, Israel was bound by morality to consent to the murder of its citizens. Could it be that this was because said citizens were Jews? Did he perhaps consider Jewish blood unworthy of justice? He didn't like that. I also told him it was a bad idea to play the persecution game with a Jew. He didn't like that either.
Incidently, I think this guy is dead right about this monolithic Leftism killing the churches themselves. Roughly the same thing has been happening in Catholic circles as well, and Reform Judaism has been shrinking steadily since the '60s--Reform is the Jewish equivilent of Universalist Protestantism, it doesn't exist in Israel, thank God.