We appear to have reached the same impasse that this highly emotive subject eventually resolves itself into.
Any perceived cover-up or whitewashing of the events may have had much to do with who was on the aircraft and where they were going - a lot of assets in one basket (sorry to mix metaphors) for the sake of what was essentially a social event. Having, by design or by accident, put pressure on the crew to complete the task in a less than perfect aircraft in less than perfect weather, it is no great surprise to me that an element of ar*e-covering then ensued by career-minded senior officers.
I haven't read the full report for quite some time but I don't remember any mention of GPS inaccuracies which I believe had been noted on the Chinook in that part of the world before.