Also....there is a whole separate issue if an instructor or skilled diver actually SEES a diver in distress, and purposely chooses to do nothing...that would be another can of worms..how to drag your dependent charges with you, and effect a rescue up on the surface..... But it does not appear that this was going on at all....As far as I can tell, NO divers on the boat or in the water, had any awareness that the Chinese girl was in any trouble....some just thought she had a gear adjustment problem, and that type of thing happens on boats full of new divers all the time...loose leaky masks, fins that hurt or are loose, not enought weight to get down, etc. If I am wrong about anyone being aware of the problem, I would hope someone will correct me here.
I think a learning point can be found in the complacency that develops from organized chaos that often present on cattle boats. The mind becomes numb to the foibles of new divers and blocks out issues that could become a major problem. No one intentionally abandons a diver in distress (unless they are a monster). Instead, they aren't as vigilant as they could be because they see something similar every day. The dive boat I use briefs divers to be alert to the condition of other divers and to promptly alert the dive crew. It's an easy fix to get a lot of sets of eyes looking for Murphy to rear his ugly head.