I know this was an unfortunate situation at the Field Day since I was at that session and witnessed it myself. The presenter should not have banged on the hive. However, before he even started he told all of us that he would be going in the hive and that people should put protective gear on at this point, and he had his veil on. This should have been a cue to everyone to have their veils on, especially since he said it as well, and Dan mentioned it in the morning at the beginning of the day. The man doing the session also warned us that the bees don't like getting coated in sugar, which should have been yet another clue. I was only one of the few that actually listened and had my veil on.
It was suggested that everybody bring a veil but it wasn't a requirement. There were alot of the people there that didn't have any protective equipment with them or were like my wife and myself.....we only own full suits. The reason people are upset is because like you stated the presenter never should have banged the hive. If the presenter knew ahead of time the bees were going to be that irate he could have made minor changes in his presentation with a little forethought and made sure nobody was stung. I'm sure that everybody there would have understood if he verbally walked them through it without actually applying the sugar if he explained he had to do it that way because some weren't protected and the crowding.. The cumulative effect of this presenters blatant disregard for common sense and common courtesy left a bad taste in more than one mind that day. Alot of the people there that were less than impressed didn't get stung and DID have protective gear on. My wife and I were at another presentation when all this happened without protective gear and managed to to remain sting free all day.