Aiki is not blending in external movement of joined centers like that. That idea is a modern corruption. Aiki is about changing your own body to make a powerfully balanced dynamically stable platform that neutralizes and controls and leads on contact.
THAT is why Ueshiba said When I move my body-techniques are created.
I was going to ask how this would translate into dealing with an incoming strike to the head, which I assumed you would respond to with an external movement or "waza" (though of course driven by internal movement), but then I thought of the systema striking exercises I've seen where people practice (I think) how to neutralize the incoming force in a relaxed way. Does that more or less represent an answer to my question? ...I assume because the head has so litte tissue compared to the torso it wouldn't be able to neutralize/direct the force into the ground as well. Am I in the right ball park?
Also, would it be fair to say your understanding of aiki is that it is an "internal" practice, but that most Aikido practicioners are doing an external practice? And that while external arts can produce a strong capable fighting body (when practiced with adequate "fight" pressures), internal arts are superior?
Hope all is well!
p.s. I dont know if these questions seem useful or not...I'm just trying to "refresh" my approach to these conversations and establish a kind of baseline for that. Any thoughts you'd be willing to share would be appreciated!