The article you gave regarding what the theatre said showed that the theatre's comments were entirely based on hearsay. They quoted what the man in question saw, and a witness (which contradicted what the man said).
So as far as reliability is concerned, it's not really any better than the other people giving accounts/interviewed. Only once a lot of accounts are received is anyone going to be in a conclusion to draw conclusions.
What's pretty much universally acknowledged is why/how it started (standing ovation floor the show not for the flags) and that the comedian challenged the man in question and became abusive to him swearing and telling him to leave.
Most accounts don't marry with the man's that Jewish people were asked to leave - very few accounts mention that Jewishness was raised at all (the witness with the theatre said it wasn't mentioned). If more come forward saying it was, I'll obviously reassess that view.