I have followed this thread from the beginning but hesitated to post. My disclaimer is that I am mainly a recreational diver operating on the fringe of technical, some deeper depths, short deco, 2 gases. I am also a simpleton and reduce things to the basics as well as seeing most topics in black and white, right and wrong. If I have a buddy, I have an explicit responsibility to assist that person in case of trouble, including OOA. Of course, I do expect my buddy to dive in a responsible manner and not place us at unreasonalble or unexpected risk. With my family, that works extremely well, with an instabuddy, that works variably. If one is diving solo, one does not expect to be responsible for others. Of course, one may encounter a diver in distess and one would naturally attempt to assist in any way, within reason.
There comes the differences and the difficult choices. With my family, I would risk my own life to save my wife, son, or daughter. With another buddy, I would always do my very best but would likely be the most likely to survive, same with an unanticipated encounter. What if I were the one in need of assistance, though with the exception of equipement failure that would not happen, I would expect the same of the diver I was with, planned or unplanned.
Obviously, preparation and avoidance of these types of situations is the best medicine. I've never been OOA and have never encountered an OOA diver in 700 dives. I suppose it is only a matter of time until my experience changes. I hope that I am up to the challenge to optimize the outcome for all involved.
Good diving, Craig