The report says the man "advanced" on the officer. If he was charging him the officer may not have had the time to take careful aim but went for a center of mass shot. It is surprising how little time it take for someone running to close the distance between them and their target. IIRC, if they start running at you from about 15 yards away, you'll be lucky to get off 3 or 4 shots (let alone hit them, if you're moving away too).
Too bad we don't know what "advanced" means here, though...