IMC ???
I fully and absolutely concur your feelings with regards to blame. The aircrew CANNOT be negligent unless you are absolutely certain what happened and as a Curent and operational member of Her Majesty's finest aviators I would back those guys up till the end....
However, Why did they fly into the hillside?
Did they see the hill side? Why didnt they see it? If they were VMC then they would have clearly seen the ground and been able to avoid it. If they were not VMC then they MUST (r) MUST climb to above the safety altitude.
Notwithstanding that, it seems certain that the guys were doing what they were trained to do and if that is the case then the training is incorrect and therefore they CANNOT be negligent...the system is.