That's all well and good, but I would think that the decision to pull the trigger would crystallize fairly quickly as he sees the butt of a gun being withdrawn from under your jacket/out of your belt. I'm not saying don't defend yourself, as the situation allows. What I'm saying is: A) CCW is not the panacea so many make it out to be and B) MOST situations where a gun is already drawn on you will not allow for you to then go for your own gun or to make a move.
You would think that, and you'd be wrong. It's obvious from your analysis that most of what you think you know about firearms and use of deadly force was learned from years of cop shows on TV and action movies.
The criminal didn't expect the victim to fight back, do you really think he'd expect someone else to have a gun too? Do you think he'd recognize it as it was being drawn and presented? Having a gun drawn on you is a very rare occurrence for the vast majority of people. Police go through hundreds of hours of training just to be able to recognize it when it's happening. You really think some punk criminal who wasn't even expecting resistance would be able to recognize the threat and respond in under 1 second? The guy got picked up waiting in line at the same GameStop, clearly his situational awareness was lacking.
You are correct about point A, there are no panaceas. But with some training, practice, and personal situational awareness you can quickly take the initiative and switch things up even when someone else has the drop on you. And that's a far better position to be in than hoping the guy with the gun doesn't shoot you anyway after you comply, either intentionally or even accidentally.