He spent those 3 seconds wisely. He was up out of his chair, moved to put the desk between himself and the threat while he was drawing. He made his first shots around the right side of the desk, them moved back and to the left putting distance between him and the threat, firing all the while, ending up on the left side of the desk where he had a clear line of fire all the way back out the door.
Those were all instinctive moves. Perhaps he had rehearsed what he would do in that situation in the long hours of boredom on the job.
Whatever, he was quick and decisive in his actions....probably quicker and nimbler on his feet than he'd been for awhile.
A great job.