I suppose this accurate in terms of the 'fundamentalism' argument, but their views to have 'nothing' to with radical leftism is impossible.

I specifically said that their views have nothing to do with Judaism, because they're as orthodox in their religiosity as the average Unitarian or UCC-member. Basically, Social Justice with Jewish trappings is their religion. Which is why my argument is that this has nothing to do with Judaism, just like UCC and Unitarianism today has nothing to do with Christianity.

If Social Justice was caused by Judaism, then you would expect the people who are most committed to the Jewish religion to be the most SJW. The opposite is the case. Orthodox Jews are generally very anti-SJW, and they are faithful Jews, while Reform Jews who are about as Jewish as I am but with fondness to mutilate little kids, are the most SJW. So there is an inverse correlation, which to me suggests that Social Justice and Judaism are actually incompatible.

We wouldn't see Jews massively over-represented among SJW's if there weren't something about the religion/culture - even in its secularized, largely non-practicing form

I think there is something in their culture. Namely because of what happened to them, an oversensitivity to 'racism' - which is why they side with black identitarian movements as supposedly fighting for justice, when black activists actually hate the Jews.

Something about being a non-practicing Jew drives people toward radical leftism.

I think so as well, though there are also many differences between Jews and non-Jews that account for part of the difference.