The thing is, you pulled a gun out towards someone who already had his own gun AIMED AT ONE OF HIS NCOS. While you were trying to make a joke, you did say "I am joking" the second you got your head blown off your shoulders, therefore you can't really blame him for doing that. I would have done the exact same thing too if someone pulled a gun on me from the back and already had my own gun off safety.
While you could void that and carry on without any PK consequences, you went a step further, insulting and THREATENING the same man that opened fire on you seconds ago without much thought, completely failing to read the situation. What did you expect to happen? Let you go and get a gun so you can have your revenge? Absolutely not.