Very good post, I think posting actual accounts like this in the Rescue course would probably be very helpful (I haven't taken it yet). The problem with this type of theory is it's taking one bluemap and applying it to all situations, it seems like everyone there did a good job of using common sense for the most part, and you noticed the two big mistakes you did make (the snorkeler leaving, and not noticing the DiveMaster in shock). I've also go tot say that given you're a Divemaster and I assume have a pony bottle, the choice to temporarily go solo in relatively shallow and safe area (I assume since you had a OW class) seems like pretty low risk given the situation. I wouldn't have done that myself due to my inexperience, but if I had more dives and training under my belt, I probably would have made the same decision.
The three things that did stand out to me, however were:
1.) Someone telling your OW class to join the search is obviously an extreme example of what you were saying, but it made me think of a more general question. Were there only two dive teams because those were the only people there ready to go and qualified, or did you purposely want to limit the number of people to avoid confusion?
2.) When you talk about the diver foaming blood, you mentioned the mental aspect. But is there any danger to the rescuers here, especially if they were not in a drysuit? I know there are certain diseases which can be transmitted through blood and if there were any open wounds (even if not known about) is it possible for infection? Or is the blood too diluted from the water for this to be a concern?
3. The divemaster going into shock was truly eye opening, I guess being a newbie diver, you kind of see the veteran divemaster as being invincible and able to save you if something goes wrong, the fact that he became not just useless, but a liability, is a little bit scary.
But hearing this definately makes me realize I need to take the Rescue Course sooner rather than later.