There should have been no thinking at that point by the officer. That's why we train, train, and train even more. All the "what ifs" should have been done by then regarding what you're going to do if a bad guy points a gun at you. Sure, you've got to make sure you're behind cover if it's available (it was and he was) and know what you're background is down range (not a problem here).I feel it’s more an example of thought time, not reaction time.
The bottom line is that he had plenty of time to take care of all of that and this was not a situation that he was rushed into. This officer made the decision to not shoot the first time the BG pointed the gun at him (100% of the officers that I've spoken with who have seen this video felt that he should have shot him right then) and that time it turned out OK for him. It seems pretty obvious to me that if the BG wanted to shoot the officer he had at least two times to do so. The second time he could have easily shot him and even though the officer ducked his head behind a tree he would have still probably gotten hit in his exposed arm.
Again, the purpose of this video was not to criticize whether the officer did the right thing (he went home safe and that's what matters most) or not, or even if this was a suicide by cop, but to show how fast some one's actions can be and that there is a "natural processing delay" between your brain and your trigger finger.
KBCraig - tell me how you did that and I will get it edited - thanks.