I think he's words may have been wrong as he had not fact checked.
I do not believe he was antisemitic
He said that Israel 'deliberately took the security off ' and 'allowed the massacre' to happen. And you think that he should/could have fact checked this?
He said that Labour's suspension of another MP was 'driven by people in the media from certain Jewish quarters'. And you think that had he 'fact checked' he would not have said this?
Either you are extremely naive or something much worse but you seem unable to recognise anti-semitic tropes when they are staring you in the face.