AnFI - you do come up with some odd things sometimes - if the aircraft was descending vertically and spinning about the rotor axis, your theory (have you practised that technique) might be valid - BUT, in both the 139 video and the Welsh Lake (Not Vyrnwy but LLyn Peris) the aircraft had forward speed so pushing forward on the cyclic would assist.
I know you are an expert on all things aviation (you keep telling me so) but I knew the pilot in the Wessex and visited the crew in hospital the next day so I have a pretty good idea about what did and didn't work in that case.
Do you do much currency training in a twin simulator? Plenty of us here do and have done countless TR drive failures from different speeds and heights - moving the cyclic in a circular fashion to match the rate of rotation is not a recognised or even slightly valid technique.