I have not heard back from anyone on copying the post.
Gombessa, there are two caverns involved in the story. The cavern at Jackson Blue is a very large opening with very high flow coming out of it (at least under normal conditions). There is a very little silt, and it would be extremely difficult to silt out at least the front of the cavern, to the point where you couldn't figure out where the exit was. This is the type of cavern that is seductive to untrained people, because the risks probably ARE fairly low, if you don't go in very far and if you stay in the very open part of the space. Where people get into trouble is that they keep pushing how far they go in, or they swim into corners that turn out to be passages, or otherwise set themselves up to fail.
But you could do a fair amount of swimming around in there and convince yourself that caverns were pretty benign.
Then you go to Twin, which, as you can see from the video, is the polar opposite of JB. The entrance is smaller than the space behind it, and that space is small, too. There is very little flow, and the bottom is silt and mung which is easy to disturb and which doesn't settle quickly. This is precisely the kind of place that really NEEDS cave skills to be handled. No open water diver has any business in Twin; I might even go so far as to say that most recently trained cavern divers would be well advised to stay clear of it.