I've banged on about these 2 f**kwits before but it is not somewhat suspicious that they lied about their endurance on the flight plan and would not state what their actual fuel load was.
To then end up in the water less than an hour after their theoretical endurance (according to the report a little over 3 hours) rather smacks of getting caught out and running out of fuel and blaming the cock-up on mechanical failure.
Does anyone really believe you can climb onto the skid of an Robinson in autorotation, jump off at 20 feet (entangling the inflation cord of the dinghy as you do so) and still be able to turn the aircraft away and settle it gently on the water.
Sounds like a power-on ditching when they realised they could not make landfall due to lack of fuel.
The rest is a fairy story.