LW50,
Yep, the Training Captain's overriding purpose for being there was to exercise supervisory discretion to prevent exactly what occurred.
He was the linebacker, the free safety (pun intended) and the goalie....and he dropped the ball....
....regardless of the fromage, the ancillary findings or the excusatory human factors findings. All of which he was put there to deal with (including the fromage).
I get weary of the view that this class of accident somehow provides wonderful opportunities to learn from and improve the system when there is really no novel magic reason to be sought out to 'explain' what absolutely shouldn't have occurred with existing knowledge levels and within the current system. Every accident is not revelationary, some just sad repetition.
And relative to higher experience levels....
On a 727 recurrent training flight with an 'on paper' very experienced ex-airline type, the FE instructor who had flown with him previously as his pilot instructor passed me a folded note that said,
"Roger is capable of surprises."
Training Captains are specifically there to minimize the effect of any such surprises. That is the job, however there's always that bell curve lurking.