I think the required liability coverage for SCUBA providers is very high, and I know HAL will not use any shore excursion providers who cannot carry the required amount of liability insurance. They were probably finding that limit even hard for their own in-house people to meet, so decided to discontinue SCUBA on their own private island.
I noticed that when I took HAL to Hawaii and the South Pacific in January 2006, there were absolutely NO SCUBA excursions offered on that entire 30-day itinerary through HAL. I had to book my own independently through Top Dive. When I asked the Shore Excursions lady about this, she told me exactly what I posted above. The liability insurance limits on "high risk" excursions are very high and most of the excursion providers in these ports cannot meet HAL's requirements in that area. So, HAL can't use them.
Blue skies ...