Bruce you are now just teasing...you KNOW that there is no clear legal or philosophical answer to your question
As for negligence, that is something that i know a fair bit about. It is a little complicated because the various states and territories have different good samaritan legislation, so I am going to assume there is no such legislation for the time being.
Assuming non-professional rescuers (who have their own peculiar difficulties), there is ordinarily no duty to rescue. That is the main problem with this case. Let me say again, there is ordinarily no duty to rescue. So no matter what your qualification, if you saw someone drowning in a swimming pool or the ocean, you have absolutely NO obligation (legal anyway) to do anything to assist.
Now, the question is whether there is something inherent in the nature of the buddy system that changes that. That is not a question that could be confidently answered in the absence of some case that decides it one way or the other (and I am not aware of any). But in my view there is nothing in the nature of the buddy system that imposes such an obligation. Now, it might be that in certain circumstances there is some super-added factor whereby responsibility is assumed by the buddy...perhaps in the circumstances postulated where an orientation dive was refused on the basis that Gabe had assumed responsibility for Tina's welfare. But ordinarily, I would think no duty of care.
I do not think it is clear in Australia whether or not there is an obligation to continue to rescue once you have commenced. It seems an odd position to me...if you don't have to start why can't you stop? One reason might be because having started others may not have come to assist. But if there were just a victim and rescuer, then that could not be a factor.
Anyway, it seems to be generally accepted in the text books (based, from memory, only on some North American cases) that there is a duty to continue.
Noe, of course the standard of care is one of reasonableness. I don't think danger to the rescuer removes the duty of care. It simply changes what is required in order to act reasonably. In other words, if there is danger then you can reasonably cease the rescue (or change the course of the rescue).
Now, one needs ot be careful in characterising Gabe's decision as an abandonment of the rescue. On his version of events, he was in fact continuing his rescue efforts by trying to get help. Now, I don't want to debate whether that was good practice etc but simply point out that there are many different ways to render assistance.
Finally, and again at the risk of being flamed, I don't think that the fact you are certified as a Rescue Diver necessarily means that you have the skills necessary and the wherewithall to use them in every situation. While one hopes that having been through the training you won't panic when someone gets into trouble, I think it is unrealistic to expect otherwise in all cases.
