Hard to solve.
An accident that occurred fifty some years ago has to be harder than solving most cold cases. The technology in the early 60's was very poor to what we can do today. The 1961 investigators, I'm sure did there best, but you are looking at it in todays time frame. I think your conclusion may be accurate, but will that ever change the historical outcome?
Frequently, in cases where the crew does not get to defend or tell their side of the story, the operators loose. The aircraft manufacture, maintenance crews and company are all there to deflect the fingers away from there possible contribution and point at the crew.
Just my couple of cents. Very sad but true.