I don't think that is true. The reasonable fear of great bodily harm is enough, I believe.
I've asked others to describe just what was the attacker going to do after throwing the popcorn if he hadn't been shot? One poster suggested that he would just turn around and take his seat; as if he was anticipating no retaliation whatever. I can't picture this.
At the very least, I believe the popcorn was an attempt to get the ex-cop to retaliate physically so that the attacker could give the guy a beat down and feel justified in doing so.
Here's a hypothetical for you: Imagine that it was the ex-cop who threw the popcorn and then the texter retaliated by punching the ex-cop repeatedly until the ex-cop, on the verge of losing consciousness, draws his gun and shoots.
Is that a good shoot? Does the ex-cop get a free ride to throw objects at the texter to goad him into physically retaliating?
Imagine Zimmerman if he had thrown the first punch. He'd be in jail now.
“The reasonable fear of great bodily harm is enough, I believe.”
You might be right if there was reason for fear of great bodily harm. I don’t think that throwing popcorn goes anywhere to that level. And if you or I had shot someone for throwing popcorn on us we would rot in jail for the rest of our life.