Plus there's a food & drink minimum of $25, which they still made you do even if you already late.
At a 54 Below show I went to, literally maybe 20 minutes left, a mom and her two daughters came in (judging by the Playbill & the plastic drink cups, they just came from "School of Rock" which is even close by) and was seated at my table. The concert was already in full swing and they had to settle in, had to discuss what they were ordering, actually order, etc. It was just distracting, especially as there was quieter songs during their arrival & order.
I would suggest not to come late to the 54 Below show and just see if you can transfer the amount you paid for your ticket to another show.