Reports so far indicate that feather unlock was selected outside of design parameters.
Looks like it might have been an oops moment. And sophisticated systems just should not allow oops moments.
The problem is that you must be 100% sure you can feather the tail for reentry, or you will die. If there are too many safety interlocks that can prevent the tail from feathering, you run the risk of those interlocks failing to unlock the tail when you need it later.
The best design is probably a simple, reliable mechanical lock, and redundant feather actuators, so you can feather the tail after any single failure in the unfeather system. A mechanical unlock system relies on the crew leaving it locked until it is safe to be unlocked (i.e. after the end of the rocket motor burn and the EAS is less than XXX).