I have heard from trainers/decoys that a large dog's head/skull area is extraordinarily hard, to the point that you'd more likely break your knuckles than dislodge a determined biter by punching it in the head. If true, that might make sense as dogs evolved as coursing hunters whose heads would be vulnerable to bigger prey hoof strikes.
Punch it in the brisket instead of the head? I don't know. I once struck a Labrador in the ribs with a bike wheel at over 30 mph. Not intentionally, he came out of a ditch and was chasing me and a couple others. When he cut in front of my wheel, it launched me over the bars and broke my collarbone, which is now improved, rust free titanium in part. Best I could tell, as it was not really my main concern, the dog was OK, maybe a little sore in the ribs as he trotted on off. Point being, dogs are tough and when they are revved up, they don't quit easily. Hence, the adjective "dogged." Or the old dated slang verb "to dog," as in Larry Bird told Magic or vice versa, "I'm gonna dog your [keister] all over this court."
Back to subject, I'm a novice at Schutzhund, but have gone 1-2 times a week since March, minus COVID break. Some days, police K9s also show up and do protection training with apprehensions.
I've seen some of these dogs slow to out from a bite, some a little nervy from blank gunshots (honestly, their handlers see it and remark on it; I might have missed it otherwise).
I've definitely seen one or two prance around with the sleeve a good little while before coming back on command. But I have not seen any get over-revved and go at the handler when getting harnessed up for bite work. Granted, it was practice bite work, not the real thing. But even our two non-police K9s get pretty jacked up for it.
I don't know enough, either from the flawed media or just about handler-created issues in general to judge. But assuming the dog had one arm in a hard bite, his options might have been limited?