Unless the machines in the GOM are set up different to the rest of the offshore world i doubt them flying into the sea in the cruise would have been the cause.
It should have had a serviceable SPWS (Surface Proximity Warning System) which warns the pilots when they are decending through 1000' (depending on their company NOP's) and then another more urgent warning decending through 100'. I doubt given the type of operation and experience of the pilots that they both would have ignored such warnings.
On an offshore operation with two pilots, decending into the sea at night would be more likley to occur on approach to a moving vessel than in the cruise!? This is one of the reasons why this type of operation has two pilots.
Recently in the UK a 76 suffered a main blade failure from lightning damage.
This accident sounds very similar to that.
Let's wait and see what the ATSB come up with before we jump on the blame the pilots bandwagon.
The poor bastards probably never had a chance RIP!!