As far as him being annoyed by the texting goes, all he had to do was move to another seat, but no, he wanted to demonstrate his authority like back when he was a policeman.
If the textor had violated any law[s] previously, there was an off duty Deputy in the audience with the authority to arrest him. He took no action. That, in and of itself, says that the victim violated no laws. Now the cover and getting him off begins.
He did take action. He went to the theater management/staff and complained. When he returned, the dead a-hole badgered him for "tattling". Things escalated from there.
It's like when you are stuck in a traffic jam and some a-hole decides to jump traffic by speeding on the shoulder and cutting in front of a car, then gets all hissy because you hit your horn at him.
They know when they are being jerks but they can and do get violent when they are called out about it.
That's how it strikes me, as well.