I guess that if both Shioda and Chiba used that phrase the only conclusion must be that it came from O-Sensei!
I find if I let my fingers open when drinking a pint I just tend to waste beer...
Asagao or morning glory hand , didn't...come....from " Osensei" it came from Takeda " Dai sensei"
The idea is not to have the fingers spread spuriously or arbitrarily. There are specific things to do with intent and reasons for them none of which has anything to do with:
Extendors and retractors
Kokyu...ki...intent... are sounding more like buzzwords in the mouths of budoka than actual useful tools.
It's too bad teachers can't get their collective shit together and talk plainly and in a beneficial manner on the occasions when they actually posses useful information. It would at least help people differentiate between B.S. and helpful advice.
The former being far more prevalent than the later.
The training model has nothing to do with the hand shapes anyway. It's what is happening in the body. Once we know " what" to work, we become more free to understand what must be retained and what can be let go of. When I spar my hands are free to do whatever is appropriate: grabbing, punching, leading and hitting again without loss.