Anchorhold
As for military authorisation, that did not make a difference in the CFIT Chinook accident and various other RAF CFIT accidents.
I didn't say it was infallible but it is a layer of safety/supervision that doesn't exist in GA.
The Mull crash had a lot more going on than just a simple CFIT - I have seen several military CFIT crashes discussed at length on various mil flight safety courses - including that one - the auth process is a check and balance but ultimately if the captain doesn't comply with his auth there's not much you can do.
Rotorspeed - I think your logic is sound regarding the use of the VS mode but without a CVFDR we won't ever know.
Every pilot should study this accident to try and understand how poor practices can too easily convert a serviceable aircraft and several humans into a scar on a mountainside.