fdr, very sad to read that you're done here, your musings were always one of the main reasons i (and probably many others) are reading these forums.
I don't have a lot to contribute other than anecdotes of my experience: an inadvertent left pedal stomp by the student on a simulated power loss in an R44 and R22 does put the machines into an absolutely hair-raising flight state, as you said. It happened to me once in each, during about 10 years of instructing on and off, and in both cases the attitude deviation and rotor RPM loss (mid to low 80s) was what I as a non test pilot would call "extreme". Despite my immediate intervention. I obviously survived both, and there was no damage found, but i can also easily imagine that a slightly different set of entry parameters could have caused structural failures. It would've been interesting to have had a camera in the cockpit, but no such luck.
The instructor in the accident machine has been identified, although i don't know if this information is public yet so i won't go into it. It is a very tragic affair. One thing that is perhaps relevant about the person is that they almost certainly attended the RHC factory safety course somewhat recently.