<< … the crash site evidence strongly suggests that the aircraft was not in control immediately prior to the crash.>> No it does not.
All the control pallet springs detached and the pedals 70 degrees over, hardly suggests being in control, Walter. I know the DS (or rather the WD) solution is the first was impact damage and the second the famous "escape manoeuvre" but evidently that relied on the Boeing Model which in turn relied on a 1,000ft/min ROC which even allowing for manufacturers' rose tinted estimates of their product's capabilities was way off the mark. Instead of reverse engineering the accident back to prove the pilots responsible the BoI might have done better to have the AAIB seriously consider the clues in the wreckage. But then that might have lead back to the lack of Airworthiness condition known of at RTS. So which to go for? Tricky....