Punto - I think the fact that they hit a rock they didn't know was there calls into question the 'well-surveyed' element and I'm not sure how often Blacksod does get used, especially by East coast crews.
However, I fully take your point about the conduct of the approach, but until we know what the CVR says, we won't know why they chose this approach or elected to letdown to 200' so early in the procedure.
There were many more options available to them since the S92 is such a capable machine, the SAR type letdown isn't inherently dangerous but what it appears they did doesn't follow what I would call normal SAR protocols.
If the rock hadn't been there, they would still have been faced with a 10-mile transit at 200' in the dark, downwind with any go-around being towards land - not my favourite sort of option.