The antler-seeker started shooting when the bear was 10 yards out. It is likely the early shots slowed the bear a bit, and might have deflected it a little.
It is not hard to fire 10 shots in two seconds.
The record holder fired eight accurate shots at close range from a revolver, in one second.
It probably took the bear more than two seconds to cover the distance.
Of course, that was Jerry Miculek. As a shooter, he is in a stratosphere of his own. He hit a balloon at 1,000 yards with a .44 magnum revolver! It took him 4 shots but the other three shots were near misses which just proved that the hit was not a fluke. Jerry and his .44 I'd be pretty confident against a charging grizzly if Jerry Miculek was between me and the bear with his .44 magnum. I'd guessing though if he had a choice for that situation, he'd be armed with a rifle or shotgun.
Your point though is spot on. Someone who is experienced with a pistol can get off a lot of shots off in a hurry.