But it would not have involved excessive G anywhere near limit.
Yes, but of course it's possible that the elevators & associated tabs etc. could be pushed closer to their ultimate limits than perhaps evident by the aircraft's overall G loading.... And when you combine that with the issue of whether these components had grossly exceeded their "safe life" as I believe was inferred in the recent "Tradgedy At Tuskar Rock" book (and not mentioned in the 1970 report) then perhaps it was just an "accident waiting to happen".
It does sound like tab flutter is the most likely cause of -AOM's crash. As 383656 points out above - comparison with the PK-IVS crash is very interesting, although the final mode of crash is different with -IVS finally losing an elevator after prolonged tab flutter, the crew losing control and the Viscount diving to the ground.