NLB, the accident was in at least 3 Cozumel papers the following day. That's where I found out about it. (There's 4 papers that I know of that are online and if you don't read Spanish you can view them in English with any web browser translator). Deaths and accidents to divers, snorkelers and swimmers as well as tourists involved in any kind of accident are reported in their papers when they happen. Considering the story had slight variations in the different papers, and that no details of the divers medical history or actual cause was known at the time, I'm really not sure what exactly you'd want the shop to tell people. All announcing this tragedy to customers would do is raise questions to which they had no answers, and cause speculation dn unwarranted concern about the shop and its staff. And quite frankly, I don't feel it's their place to discuss it with anyone. It's a private matter for the family.
If a shop or its staff are negligent and their actions directly result in injury or death of a diver, then yes, I would absolutely want to know about it and that would definitely factor into the decision of whether or not to dive with them. An unavoidable medical issue and resulting tragedy has nothing to do with what shop someone was diving with and if owners or staff started telling everyone about it, I would actually see that as being somewhat unprofessional on their part.
I'm in EMS and part of a dive team. Most of what I see and hear never makes the news and nobody other them those immediately involved or on-scene even know about it. That's the way it should be. Anything other would show a lack of professionalism and a lack of respect for the victim/patient and their families.
Also, as an aside, read the fine print with cruise lines and resorts. Just because they don't put a piece of paper in front of you sign doesn't mean you aren't waiving liability on their part. Even with the waivers we all sign to dive, how many people really check off everything that's applicable to them? If you look at those forms you'd think divers are the healthiest bunch out there - never any sinus, allergy, ear issues, we never take any medications, have no medical conditions and have never had any kind of surgery....
DMs are guides. Most do assist their customers to the best of their ability if there's any distress, panic or other problems. But they don't have a leash on each diver and aren't babysitters. A really hard part of any rescue situation, is the rule that you don't put yourself in a position of becoming another victim. Stopping someone who's making too rapid of an ascent you really have to be careful and recognize that if they get too far ahead of you or you can't control them, continuing the pursuit could put you at risk for serious injury or death. A choice you never want to be faced with, but the reality is that you'll be more useful to the victim if you make a safe, controlled emergency ascent and tend to them when you get to the surface, even if it's not immediately with them.
From the accounts I've read, the crew and people that met the boat at the beach did everything they could. I hope you are never in a situation like this in any capacity, but if you ever are, you'll look back at this incident with different feelings I'm sure. I have no doubt that all involved, and even bystanders who witnessed it all, have spent a lot of time second guessing their actions and playing it back in their minds thinking if there was anything else they could have done even though logically they will know there wasn't. It's hard enough to deal with and they don't need a customer who feels he should have been more in the information loop beating them up. While you're feeling disgruntled because nobody told you, there was a family who lost a father.
IMO, the shop showed good judgement and a lot of professionalism in a very difficult time. They had a commitment to their customers, put a smile on and made sure that vacations continued as planned. I wouldn't think for a minute that that was easy for any of them but it was the right thing to do.