I bow before your aircraft certification expertise! You must have a lot of experience to make such a decisive statement
err no its in the ATPL syllabus and also it was in a selective course during my engineering degree.
From memory the original 747 design didn't have one because it was in limits during test flying. Then when they stretched it with further models it wasn't so they had to fit it.
The reason why the Pc12 has it is the huge torque delivered by the prop/engine and it wouldn't be controllable with max torque and stalled wings.
So its a completely different kettle of fish, you will die if you stall a PC12 and put max torque on before unstalling the wings.
Cirrus they couldn't be bothered finding out and used the BRS as and excuse not to test. In all likely hood you would be able to recover normally its just nobody knows. Well they more than likely do but nobody will admit to it.