With all due respect, Ken, this forum isn't just a place for the official conclusions to be posted. I don't see any reason why people with first-hand information should necessarily only communicate it to you or "through the proper channels", privacy and liability issues notwithstanding. That said, I wholeheartedly agree that uninformed speculation is unhelpful at best and harmful at worst.
I spent a lot of time last night reflecting on my personal observations yesterday. Three points stand out to me as significant, regardless of the eventual determination of the cause of the accident.
First, I was greatly impressed by the immediate and decisive response by many of the divers at the scene. The rescue efforts may not have helped, but I do not believe they could have been handled any better. Well done.
Second, all divers should continue their training at least through Rescue Diver. Immediately before the accident, I was talking with a student about taking an upcoming rescue class. Afterward, he said, "I had no idea what to do when that happened. I guess I'm taking that rescue class after all." There's no such thing as being too prepared. Someday, instead of dozens of skilled responders, any one of us might be the only person available to help.
Third, buddy awareness and communication are essential. Yesterday, a significant amount of time passed between when the victim was discovered and when the rest of his group was identified. Anyone who leads dives knows that it can be very difficult to keep track of all members of a group, especially when viz isn't great and there are lots of people in the water. Be certain that students know to maintain close buddy contact AND how and when to communicate to the DM or instructor that their buddy is missing. I'm going to revise my own briefings to include more specific and detailed instructions for such an event.