Well I did not know that there was a requirement to have a minimum ppl but preferred Cpl to comment!
This high standing opinion of many pilots is what kills so many.
The amount of times over my +30 years in aviation I have been asked by very high time and including ATPL pilot , what does this do or how does this work on a basic system is amazing. Many tech logs/MR,s entries cleared with "tested no fault found" should also include "Pilot trained to use it properly".
It is simple, this Mallard stalled. There is no evidence of any external or mechanical factor that assisted in the stall. There are whiteness and video footage in abundance - The ATSB should not need a year to do this report.
P.S. sorry to all the PPL, CPL & ATPL holders that do know others in the industry also know how aircraft work and fly.
Condolences to those poor kids.