What a sad news
. My condolences to his family and friends.
On a charter does mixing recreational divers (who want to get to there dive site and enjoy what they came for) with students doing speciality classes (which the rec divers must sit and wait) give a feeling of being hurried ?
Most of the time I've been on the Monterey Express with a deep class, the boat use to go to a site where rec divers can dive at the same time than the class (for ex, Mono Lobo, Ballbuster). On saturday, the weather conditions in the morning led the boat to go back in the bay for the second dive. So I guess the choice of the mile buoy in the afternoon was a good compromise between the necessity of finding a calm and enoughly deep dive to have the class run but it's already too deep for rec diving. Ballbuster was probably undivable. I've been in both situation (the rec diver who waits for advanced divers to complete their deep dive and the advanced diver). Never been troubled by the fact some had to sit and wait for me or I had to sit and wait for them.
While it is useful to have a visual reference when ascending, an anchor line really helps in descending when divers need to reach a particular position at the bottom (a pinnacle for ex) but you can have more stress trying to reach the anchor line if you have some currents at the surface than just drifting if the anchor is not needed and you know the boat will pick you up after your dive wherever you are. On Saturday morning, we had both strong surface currents in and outside the bay. Maybe the conditions at the buoy in the afternoon were better for drift diving. Btw, it would have taken more minutes to reach the Breakwater if the boat had to recover a 130-160ft anchor line... The captain of this charter is never reluctant on safety. He insists for divers to use the anchor line on some sites where topography can lead to arrive in too deep waters. If he didn't drop the anchor, I think he probably had a valid and safe reason not to do so.
Stress underwater is something you tend to handle more efficiently with experience. A "Rescue diver" looks like to me as someone who has some diving experiences. Lots of things are confusing here.
From the various reports, I think the accident was more a consequence of the "Buoyancy problem" because apparently the diver reached the surface and tried to go down again. Looks like, for some reasons, he has been unable to control his ascent. It can be a lost or dropped weight belt (but in that case, if you want to reach the surface, I don't see why someone would then try to go down...) or something else.
Lots of informations are missing. I hope we'll have some constructive explanations about what happened. Unfortunately It won't bring this poor diver back to life but I guess his family and friends and lots of people here want to understand what really happened underwater.