In the past, far Left anti-Zionism was a mix of Stalinist anti-semitism and class analysis. You also got the identity crisis of Greenstein-types thrown in, for good measure.
It was very unlikely, until about 10-15 years ago, that Leftists would incorporate pure neo Nazi anti-semitism into their worldview, because they wouldn't have come across it, except in limited contexts, in which it was clearly marked with all the sorts of tell tale signs detailed by Modernity, in the preceeding post. Far Leftists who became neo Nazis, went the whole Hitler-worshipping hog. Most knew why racism was wrong: it a tool of the Capitalists, which divided the working classes, underpinned Imperialism, and so on. Faced with a Nazi, claiming that Israel controlled the United States, a Leftist would quickly sniff out a Nazi. His shibboleth, by contrast, was the notion that Israel is some sort of imperialist venture by the United States.
Nowadays, any web search for 'zionist' will bring up a range of articles: some clearly Left, some neo Nazi, some Islamist, some general conspiracist, and some in a sort of synthesised grey area between any of these.
You'll also get near-neo-Nazi stuff, like Atzmon's output, which is a mirror image of the Greenstein identity politics stuff, which has been presented as part of the argument on the Left by the Socialist Workers' Party. The SWP has similarly endorsed, and showcased, Islamist racists, and promoted solidarity with, and activists in, both Hamas and Hezbollah. When Chomsky whitewashed Faurisson - a man he knew to be a babbling racist - as a 'relatively apolitical liberal', it was a scandal. Now this sort of cross-pollenation is standard stuff.
Basically, the boundaries are hugely blurred nowadays. An Islamist might read screeds about Zionists by both a neo Nazi and a Trot, and agree with the general thrust of each essay.
Similarly, a woman who thinks of herself as an anti-racist can read a piece by an 'Israel dun 911' nutter, on a Nazi's website, and find nothing to fault in its content.
That this is so, is demonstrated by the case of Delich, or indeed, Jenny Tonge.
I would be amazed if any of the savvier Trots on the UCU are silly enough to say it: but I bet many of them are thinking:
"Yeah, but is anything Joe Quinn says actually WRONG?"