If Labour are fielding candidates who have not studied Shakespeare, that's one thing, but to not know that the term 'Shylock' is offensive, is to be ignorant to an unacceptable level.
Shakespeare wrote about current times, and in Elizabethan England, Jews were mistrusted and disliked, so making one a baddie in one of his plays is to be expected - write for your audience.
Now, we have rather more tolerant views, and bandying about such insults, especially in view of Labour's record on anti-Semitism, is simply not acceptable.