There are a couple of elements that I would hone in on if I were a member of the defense:
- The shooter was 71-years old (the victim 30 years his junior). The trauma of having a bucket of popcorn thrown at a man that age is exponentially greater. It could have damaged his eye, or caused him to go into cardiac arrest. As the theater was dark he probably did not realize immediately that it was popcorn that hit him. He could have thought it was any number of things.
- The shooter was a trained SWAT police officer -- clearly he understands the virtues of deadly force -- so an argument could easily be sustained that he did view himself as being in danger of grievous bodily harm, especially given the inherent flimsiness of Florida's self-defense laws.
- The article says that the victim's wife suffered a gunshot wound to the hand because she was trying to calm her husband down (by reaching her hand across his chest, presumably to hold him back.) Again, we don't see any violence from the shooter until he pulls the trigger, but we have two fairly straightforward instances of outward aggression on the part of the victim before that moment.
As for the beer thing, that's really my entire point. You pour a beer over somebody's head when you are in an argument, what do you expect to happen? You've opened yourself up to any number of things based on the insecurity of the person you assaulted. Nevertheless, you instigated -- and in the state of nature, especially Hobbes', just about anything could happen. Rule of thumb: don't be an unrepentant asshat, or you just might wind up getting shot and killed by a guy who will, in all likelihood, be acquitted (and considered a hero by some).