Well I realised that you only wanted the information to be used against the R22. But ultimately my stories comes back at about the same as everyone else.
I can't remember far enough back to recall everything about my first R22 flight. I do remember a ground briefing and then a flight. I don't remember touching the controls at a low level in the initial climb but may have followed the controls during that and the final descent. Total flight about 30 minutes, total time about an hour.
As an instructor I had the constrants of the SFAR over me and that made the procedure different as it told you what you must do and still does. Firstly before flight you must instruct the student on the controls, how each works and caution them not to overcontrol. Finally, personally I would make them aware that if the instructor asks for the controls then they are to be released.
I never had a problem in letting the person follow through with a light touch of the controls from the beginning but do know of smaller individuals that disliked this till at altitude. The first full touch or grip of the controls would be at about 1000 feet. The flight would then consist of a series of left turns until you arrived back at the airfield. Then a descent with the student following the controls. We just had a set route of 0.4 flight time. Fly 0.5 and you did the flight for free!!!
This would finish with the instructor landing it with the student again following.
If at any time you felt the student freeze or move in the incorrect direction then the R22 is a perfect aircraft to regain control as along with an instruction of 'my controls' you were able to pull down on the T-bar and place the cyclic in a completely alien position. So regaining full control. A student would let go when the cyclic moved up 4 inches especially with a swift tug and a loud command.
Personally I never let go of the collective and followed through on the cyclic for the duration of the flight. If you place your hand around the cyclic then it allowed the student an inch of movement in all directions before the controls became yours again. Basicly you leave your hand around the cyclic but don't touch it.
I can see where you are coming from but feel a first flight in a 300 would be worse to wrestle back control.
Now if the student was to put a completely wrong input in and place the aircraft into a situation of danger without the instructor being near the controls then I can't answer that and unfortunately neither can you or the NTSB.
Maybe there is a situation of complacency from a high time helicopter instructor with a high time fixed wing pilot. Or just the high time helicopter instructor.
I can't answer that as I wasn't a career instuctor just an hour builder that watched carefully.