If you'll read this sentence carefully I think you'll agree that "equates" is an over-statement. The unidentified author(s) condemn anti-zionism not categorically, but to the extent that it's used to mask a hatred of Jews. Put another way, anti-zionism is not a legitimate expression of anti-semitism, whose unredeemable evil cannot be papered over as a political problem.
One might just as soon say that objections to reverse discrimination (as one finds in the mouths of David Duke and such) are not acceptable when they're grounded in a hatred of blacks. That does not mean that objections to reverse discrimination are categorically evil, but that pleading a political argument can't sanitise a racist motive.
Ahhh... bug off!