True, but not as done in this exercise. I've been teaching scuba for a number of years now (PADI) and during any emergency ascents in open water classes, regs always stay in the mouth, just to be safe. Additionally, in open water classes, we teach to don and doff on the bottom, but never to follow doffing with an ascent without any gear. I also make sure that I'm literally standing over my students as they remove their gear to ensure they do not start to float away. Maybe I'm a bit conservative, but it's better than the alternative outcome. PADI would never allow one of its instructors to do this skill with open water divers, and if we did, we'd be on our own. IMHO, it's above what is necessary to be a good diver and it too advanced for a simple open water cert, but that's an entirely different discussion. Back on track now...I see a couple major issues here (I'm not a lawyer, but I did stay at a Holiday Inn Express last night ;-p
1 - was she an instructor or not? I have been involved with the scuba programs at a couple major universities and there is a very long approval process here. Most are concerned with liability and I seriously doubt that she could teach it without an instructor rating from a major agency. If she was approved but not an instructor, the University can also likely be held accountable. Even with instructors and liability covering a couple million, it still took over a year to get the scuba courses approved at one of the universities.
2 - was the student on drugs? If so, how could the instructor be held accountable unless it was obvious and she still allowed the student in the water.
3 - Was she directly supervising the student? How many were doing the exercise at the same time? Was she in the water or out?
Not many people realize it, but ascents, even from as shallow at 6 feet, can be very dangerous. Air is not forced out of your lungs as you ascend, you must consciously exhale (I always teach make an 'aaaahhhhh' or humming sound with your lips open). If you don't it's easy to have some serious consequences.
My sympathies go out to the family and friends of the student. It was a tragic accident. As far as the instructor goes, if she was not a certified instructor, she'll get what's coming. That may sound harsh, but as an industry, we can't have just anyone teaching scuba. That's why there have been calls for federal regulation of the industry over recent years.
Your logic is flawed. Diving is not safer with this skill than without it and it doesn't save lives. I'd seriously doubt that you can cite a single incident where a diver said "If I hadn't done that skill in my open water class, I'd be dead". There are many other ways to improve confidence and capabilities without jeopardizing the safety of the student. Reality is that this is a very complex and dangerous skill if not performed properly (as evidenced here). There must be very close supervision to the point that the instructor can abort the exercise if there is a problem. Let's just say that we disagree on this one (FWIW, I am also a certified AI with YMCA and my friend was the national director of the program for a few years so I'm quite familiar with the program).
I'll stop rambling now.