That doesn't make one single bit of difference, you should not altercate the situation. He could have notified the usher, but he did not, he started cussing and taunting someone while carrying a gun.
You can handle almost every situation without altercation it, this guy choose to altercate it.
The father did not start anything, otherwise he would have been under investigation too. So it is much more likely at this point that the guy with the gun started the physical bit too.