KG86
You say:
even if they might have been distracted by an unknown other technical issue, it was the pilots' responsibility to keep the aircraft, its pax and themselves, safe.
Yes, you're quite right, but it is one thing to be
distracted and quite another for the "unknown other technical issue" to remove the pilots' ability to control the aircraft, whether temporarily or permanently. Assumptions have been made that the aircraft was under control at impact, but there isn't any positive evidence for this and, although no
evidence of technical failure was found in the wreckage (the aircraft was in rather a lot of twisted/burnt bits after the impact), the AAIB could not rule this out. Accordingly there is doubt and the pilots should not be found negligent "beyond any doubt whatsoever" - the standard of proof required at the time. Indeed, given the lack of ADR/CVR, it would be hard (in a normal court of law) to even prove that they were negligent "beyond reasonable doubt".
As for different rules pertaining to other services at the time, this is an irrelevance as both Taper and Cook were serving members of the RAF and therefore subject to Air Force Law, not Army, Navy or any other law.
I would welcome your reasoned riposte.