Ah yes, that's something that always annoys me too. Sorry for that. But I think the implication in the direction anti-semite -> anti-zionist is pretty strong, so for this particular question I think that surveys about antisemitism provide a good basis for discussion. I'd assume that anti-zionists form an almost perfect superset of anti-semites.
edit: or maybe not, you could imagine someone who really doesn't like Jews and wants to send all of them to Israel.
Please reconsider this position.There are large numbers of Jewish anti-Zionists, whose motivations range from religious to Palestinian solidarity to just not wanting to be seen or treated as an extension of Israel. As well, there's a great many people who don't mind the existence of Israel as such but object strenuously to its expansionist settlement policy, including a large number of Israelis.
As well as that, there's a phenomenon called Christian Zionism that's popular among conservative evangelicals, which views the establishment of the state of Israel and a number of related milestones as a fulfilment of Biblical eschatological prophecy. Their enthusiastic support for the relocation of the US embassy (and others) to Jerusalem is rooted in a belief that it signals the End of Days and forthcoming battle between good and evil on the field of Armageddon. While a minority position, it's one that's in ascendancy at the moment and counts the US Secretary of State (by conviction) and the President (by transaction) among its adherents.
In short, it's complicated. This is not to say that everyone who's anti-Zionist is good or has valid reasons, many such are indeed anti-Semitic, from casual to virulent. Neo-Nazis often leverage ambivalence or antipathy towards Israel to convert people to anti-Semitism and recruit them, a technique known as entryism. And there are anti-Semitic currents on the left too, particularly among dogmatic types who think Stalin did nothing wrong (sometimes loosely referred to as 'tankies').
I think you may be reading the GP's implication in a different direction to me. While it's not completely controversial to observe that not all anti-Zionists are also anti-Semites (although I do hear some who would hold that view) it's more believable that anti-Semites would pretty much automatically also be anti-Zionists.
