I don't know that passage, but we speak about a tragic accident.
There are few things I see and where I think as outsider, why can you judge about this? Do you know ALL details? If you know all details and tell all details, then we can learn from it. But now it looks for me sometimes as there is blaming and shaming the victims (the one that survived is also a victim of course).
I read about too far too fast. Yes, that is easy from behind a computer to write. But is there an average too far too fast?
I read about some 'facts' about the time since they had done courses. Ok, maybe some time between or since sounds short. But do we know everything? Remember that we divers are human and we tend to look at the time since or time between certs. So if someone is diving for 10 years, we tend to think that this diver has experience enough to move to tech diving. If 500 dives are made, for sure most will say that seems to be enough experience, let's do a 'let us know eachother checkdive' to see how you are in the water.
If another diver has made the same amount of dives, 500, but only is 2 years certified, we tend to say no. Even if the same amount of experience is there, the same amount of harder more experienced divers, etc.
But if you don't know the time since starting diving, only the amount of dives, what do you say then?
If a diver goes to another instructor to make dreams come true, is the new instructor always bad? Do we know all the details? There is always a slowdown if you go to another instructor, who says the diver will not improve in that time?
If a diver was bad 3 moths ago, or not experienced enough, who decided or decides that the diver is now experienced enough? Maybe the diver did train and made 50 extra dives or so. If that 50 dives are made in 1 year, more people believe it.
Do we know if the restriction was the first dive after getting certified or maybe it was the 50th cavedive? Remember the diver was already full cave certified on oc. This means he could have already experience in cave diving. Then the rebreather is the only new thing in a cave. That is a big difference from seeing a cave for the first time. But an important question is, was the diver be able to control his ccr in a cave? From being certified you would say and expect yes. But the skills that you have mastered just one time are forgotten first when **** happens.
Was the diver more a natural and talented diver, or did he need to train to get at least the minimum level to pass a course? Being not talented, but have the believe you are great and talented can cause problems easier than the natural that does the same. The natural that slows down is probably the most 'perfect' person. But remember, we are all human, so we are different.
Is it possible that the restriction from 1 way is easier than the other way? So that you for example get in easier than get out? That people go in, but get in trouble when getting out?
I read about really zero viz. That is not a situation you will have often, but can this happen suddenly here?
Did the divers have experience with wrecks and had there zero viz? Also things that can be part of the 'experience' people already have that can be usefull, but is not directly cave related.
Are only people who live near caves able to get really experienced? At my diveclub there are instructors who only dive 20 times a year, and there are vacationcavedivers that make 50 cavedives a year. So who is making more experience?
And I read there was a line to this restriction? Why is there a line if this restriction is so tight? Maybe if there was no line to this restriction or passage, people with less experience won't go there?
Is the zero viz to be expected, or does this happen suddenly? We train cave divers with a blind mask most times. But remember, a blind mask does not have the same feeling as real zero viz. Where people get relaxed when using a blind mask, they get stress when they are in a real zero viz.
And remember, we are all human. And some humans like to do more adventurous things than others. If these divers are the ones that like to have adventures, do you really believe you can stop them? You can as instructor refuse or advice. And if you got refused by instructor one, maybe do the course with instructor 2 and say yes and Amen and do after the course different? Also this is human behaviour, and this can happen. People drive cars when they are drunk, even if they know this is forbidden by law and dangerous. But there are always human who will do and think they can do. The same is with diving, deeper, further, etc without experience. If you need a person to help you further, you will find it. This is also human.
The question of not taking the full tank is also a proof we are human. If there are problems, people can make strange decisions. And we will never know the answer.