It is of course true that Jews were disproprtionally represented among prominent Communists of the early twentieth-century. It is equally true that they were disproportionally represented among prominent capitalists. Hitler made much of this paradox, there is an infamous speech of his that begins: "There were two brothers, Isadore was a Communist and Moische was a capitalist." In "On the Jewish Question," Marx argues that capitalism will bring a universal secularization that will enable Jews to participate fully in civil society and thus, as he puts it, "make the Jew impossible." This isn't as anti-semitic as it might sound, since Marx also thought "the Christian" was destined to become impossible. But this process led many eastern-european peasants (from one of whom I'll bet pbman is recently descended) to consider themselves oppressed simultaneously by capitalists and Communists, and they identified the common element in these tendencies as a Jewish predominance.
Anyway, pbman's comments were indeed worthy of banning. But I'd still be sorry to see him go. I can tell you that he *does* represent a large body of opinion in the USA, and is surely worth listening to for that reason alone. As Jezza said, its not like he's looking for converts here. What harm can he do?