I really love it when people interpret the standards any way they want it. Being at arm's length to control their bouyancy has nothing to do with "grabbing and holding" a bolter. Who says grabbing and holding a bolter makes anything any safer? Holding a person underwater against their will could actually be dangerous, quite dangerous to that person, the instructor and anyone else around them. I bet you there is or could be a case were this type of action resulted in a death or a serious accident. It is just plain stupid to try and defend standards which do setup the instructor to fail in a bad situation. And that's what is being discussed here when we talk about the actions taken.
If he allowed the scoutmaster to surface without going after him, he would be at fault of breaking the standards too. It's just IMPOSSIBLE not to break the standards. You see? It's just "easy" to say he broke them because he left the two kids. But leaving the scoutmaster unattended would have yielded the same result in terms of breaking standards. He made a choice he considered in that split second the best one. It wasn't, and in hindsight it was the wrong call. But as a split microsecond decision he probably followed his instinct: one panicked diver on his own, bolting to the surface, vs maybe two calm divers who could just a minute. Again, bad call, but even if he took them both to the surface to go get the scout, he would have been breaking standards until he got to the surface with them. If he had done that, and the scoutmaster were dead, he would still be in the same scenario. You see?
The whole he broke standards because he was not at arm's length to stop the scoutmaster from bolting is NOT WRITTEN ON ANY STANDARD. Im sorry to let you down here. But the standard talk about being close enough to provide assistance with bouyancy, not to grab and hold and impede people from bolting. That's something YOUR training brought to light, not the standards. And again, I seriously question that line of training itself.
The standards need to be revised. Period. PADI expelled a member without any due process, and then left him to his own devices to defend himself. That's bad. Period. PADI should be reflecting from this case what needs improvement, instead of just defending themselves. They are not. I like that another agency put the pressure on. Because otherwise, who is?