Re: Over-Speed lock
Just guessing: the feathering tail is intended to be deployed at high speed in the rarefied atmosphere of near SPAAACE, not the 200-300 mBar at 30-40,000 ft. Probably the speed would then decrease gradually during re-entry. The combination of high speed and dense atmosphere might over-stress the structure, either directly or by producing a violent un-commanded pitch up.
It will be interesting to read the accident report when it gets released.