The NSS-CDS, NACD, IUCRR... should realise that the current attitude at the top, middle, and bottom and the current system in place of displaying warning signs is NOT working.
I have put forward a suggestion in a post long ago and lost somewhere in this thread, and that is a "license" system, web based (non-governmental self-regulatory system run by "Cave Associations"), where the diver before diving a cave has to fill a form, annex Cave C-card and Insurance, provide a "good-reason" for wanting to dive that cave and in the specifics that portion of the cave.
"License" gets emailed back, and when you park your car you are required to display on the window the "licenses" for each of the divers.
No "license" - diver takes the picture of the car and plate and offending divers and emails it to NSS-CDS, NACD, IUCRR... letter goes out to the Sheriff, Sheriff gets off his chair and knocks on the door of the "rule-breaker" and makes enquiries (especially if the cave is on public land and there is a sign put there saying "NO OW DIVERS...").
Short of that, maybe we should all stop moaning on the internet about cave diving getting bad publicity and getting closed...
...and I don't buy nobody in the knowledge knew these two characters were doing what they were doing (and press reports indeed indicate otherwise).