To be fair, all of those points were made about the C210 in general and nobody said definitively that is what happened - just one possibility in a CB, into which it is somewhat possible that the plane flew, given weather on the day and reports of the pilot's radio calls.
GG:
"VNE excursions in strong down draughts are typical"
I don't understand that - observing a high descent rate, wouldn't the pilot seek to climb? Or did you mean by this stage the aircraft is out of control and "plummeting" in a nose dive? Just don't know how airspeed would necessarily change - I thought one reason for break-ups in CBs was that one wing could be in strong updraft, the other down.