I'm a rescue diver too and I would have handled the guy differently. I would have given him a thumbs up and at the surface said, "hey buddy, your tank strap is slipping, why don't we move to the shallow end and fix it?" Then I would have gently touched his inflator hose and shot some air in his BC. You can take a diver who is not in distress and make them that way. Not to be critical, but just because you are a rescue diver doesn't mean you need to be looking for a victim.
There is an entire group of experienced divers on this board who wear MOF.
There is an entire group of experienced divers on this board who wear MOF.