Mann has also called for Kaufman to resign. He's certainly not neutral and is actively pro-Israel, not just anti-Semitic. He strongly supports the argument that it's racist to criticise Israel.
Mann is also anti-Jeremy Corbyn. Last year he accused Corbyn of being sympathetic to child sex abusers.
I find his motivation a bit suspect.
Nevertheless, Livingstone was a fool and should have known better. I've never had much time for him, because I think he's arrogant and he's so convinced that he's right and he's justified in 'saying it how it is' without looking at the wider picture. He obviously doesn't know much about history, but has picked up on one fact to support whatever view he was trying to support. I'm not even sure what his point was.
Naz Shah probably does have enemies in Bradford. She unseated George Galloway by quite a big majority and Galloway then accused her of voting fraud, although he never took any action.
By the way, it was Paul Staines (aka Guido Fawkes), who is very much right-wing, who broke the story about Naz Shah.
I'm usually very suspicious of conspiracy theories, but in this case I'm convinced that there is at least one hidden agenda.