@Janrein
I agree with that view, if the flight profile itself could lead to a situation where that reconfiguration would be essential for a safe return profile. The more speed and altitude is planned for the special test profile, the earlier you would like to know if the system is working. In the end this only ensures that the unlocking is working, but not the feathering itself.
But as unlocking removes also an important safety feature against premature activation of the system, there has to be a tradeoff between removing that safety feature ( and thus the danger of deployment of the feathering system at an unwanted phase of the flight) and risking to be not able to unlock it in a later part of the flight. As a pilot i would not bother about a system, I most probably would not need anyway (except for testing purposes) and I would acttivate it at the latest (safest) time.
Next thing is, there must be thoughts about the reliability of this pneumatic feathering system concerning possible failure modes (to the feathered position without activation), otherwise a guarded switch would do the trick to prevent the pilots of inadvertent activation of the system.
I really would like to understand the operation of the system, which parts of the actuators are pressurized by what action, wether the locking and actuating system uses the same accumulator, and what the fail safe default modes are in case of loss of pneumatic pressure. Still searching though for that information.