Anniebach Corbyn didn't defend the wall. A thumbnail image of it appeared on his Facebook timeline in 2012, with a message from the artist saying that it was going to be removed. The artist didn't mention antisemitism, and Corbyn simply asked why it was going to be removed, and mentioned the political censorship that Diego Rivera had been subject to. The most salient thing about the mural (especially when you only see a tiny reproduction) is the image of bankers playing monopoly - a common metaphor after the crash. If you look closely (and if you are alerted to the fact), you can see that of the six bankers, who are supposed to be based on real-life people, one is definitely an antisemitic caricature, and another one less obviously but equally obnoxiously so. When Luciana Berger drew attention in 2018 to Corbyn's response to the Facebook post, he acknowledged that he should have looked more closely, and agreed that it was antisemitic. But it is a complete distortion of the facts to claim that he 'defended' an antisemitic caricature. It's clear from his actual response that he assumed the censorship was because of the anti-capitalist message. He has a long record of support for Jewish causes, while opposing some of the policies of the current, and some previous, Israeli governments.