A sad day for all concerned.
The new style of investigation quite rightly forensically analyses all aspects of the operation of crew and equipment at the time of the incident however many of the considerations identified may not be directly attributable to the direct cause of the accident. It is quite right however that as many lessons are learnt as possible.
The direct cause of the accident in this case seems to be a loss of situational awareness with respect to rate of descent and or speed combined with poor external height clues and locally rising ground.
I wonder whether any consideration was given to the possible momentary distraction that concentration on the 'head up display' may have caused taking away awareness of the 'outside world' if indeed it was worn at the time. Ally that to whether the rad alt indication had any lag in any aspect of the system from sensing (in recovering from an angle of bank or high rate of descent) to physical presentation in the eye. It is possible that in this scenario that reliance on HUD to the detriment of external lookout (the brain can only do one thing at a time) might have removed awareness of gently rising ground. The rad alt has a latency in relation to topography at high speed (instantaneous v approaching).
I did read the whole SI but did not note any detailed comment to this effect however standing by to have my lack of attention to detail pointed out to me.
HEDP