Transgender Man Completely Loses It When They Call Her The Wrong Pronoun

Now tell me this was not one of the dumbest things of all time. How do people recognize whether you are a transgender person or simply somebody doing cosplay or something? It doesn’t seem like ignorance or bad intentions, it only looks like an overreaction.  The cashier obviously didn’t want to offend anybody in this situation. This person’s reaction was way out of line. Where do you guys stand on this transgender pronoun issue?