I donno, in my mind I don't think that elbow power actually refers to power in the elbows. More like how the elbow is positioned to the body and uke. And how to move it.
I've read shioda's total aikido a couple of times, and I'm not sure if he's talking about the same thing.
Wouldn't that be the same fixation, saying that it is not about the power of the elbows, and yet still just saying that if you put your elbow here or there relative to this or that and move it this way it is powerful or not in some way? Could we rather posit knee power? Toe power? Finger power? Knuckle power? Hip bone power? What is so conspicuous about the elbow here that you wish to grant it special status?