FGD, thanks for your replies. I personally don't buy off on the excuse that company SOP dictated that they SHOULD descend at any particular waypoint, the crux of the accident appears to me to be this:
The descent may have been VMC, but they tried to remain in contact with Mac Central, advising of their position and altitude as they went - remember that the crew were perceiving Lewis Bay as McMurdo Sound due to a combination of the track they were expecting to be on and the visual illusions that provided false confirmation.
So based on a mistake by the crew, thence...
So the whole responsibility for the accident is based on the crews mistaken location influenced by the waypoint change doesn't totally let the crew off the hook in my opinion considering ones responsibility during VMC operations. This type of operation being accomplished by airline crews is crazy IMHO, that's what real tour operators are for.