Barbie, you are correct. The whole point must be that a burden of proof must have been satisfied. Most SH guys I have spoken with agree that the chaps may well have screwed-up. However, the rules at the time were quite clear and it remains quite clear that the burden of proof requirement was not satisfied. This case should be no different to judicial processes such as those that overturned the Birmingham Seven judgement or those where First WW deserters have subsequently been pardoned. What is done is done, but there is still a need for the system to demonstrate that it acts in a fair, reasonable and objective manner; that is democracy.
Of course, the nature of the Mull crash also (re?)opened the Pandora's Box regarding airworthiness. Airworthiness is, in many respects, a separate issue that must be pursued for the greater good, but in this specific case is a plausible explanation to demonstrate that doubt must exist.
Perversely, I still work with people who had close friends/colleagues on the Chinook and many of them still have a notable degree of anger aimed at the RAF, notably the crew. I find it difficult to explain how their anger may be slightly maligned.