It doesn't matter what minimums were but why did they land in the water?
Possibly by the time they realised that they had lost visual reference and needed to GA the laws of physics and aerodynamics meant a water landing was inevitable.
I would guess that this was a different scenario to DFW as they weren't unstable for most of the approach. I would also put forward a suggestion that a windshear warning wasn't triggered as it would have been at DFW.
Most readers of this thread forum would not be in the slightest bit interested in the Australian regulator/investigator.