The stupidest part is that he was in a safe place. They had a metal detector at the door! He was the only danger to him in there.
You should put in a sarcasm clause, because if the nightclub had a metal detector, how did he get through?
Just playing devils advocate here. I am not trying to justify him carrying in the club.
How did he get around the metal detector? I doubt it was an airport style detector but a hand held wand. If he was inside with a gun and there was a detector that means it either wasn't in use, defective or used selectively ie; major league celebrities were exempt from scrutiny.