There seems to be a gap in the level of detail between physics and biology in the Q&A. For example quantum mechanics, do you actually claim that quantum effects are relevant to the uke(uki?)/nage relationship? From the opposite direction, does not the nervous system has anything to do with the way aiki is creating/perceiving?
Ki is not a quantum theory, it began and remains a practical one, but with observations about the nature of the workings of things that does require some delving to assure consistency before we would want to rely on it (from a physical model standpoint). The effort is simply to show that the model of Ki as oscillation tracks at least as far as classical understandings of angular momentum, and a tracks good way into relativistic and quantum mechanical territory, without seeking any durable conquests in those areas.
"Substance" as such is a very knotty problem at the quantum level. Quanta are a theory of substance. Ki is a theory of operation. We only know the "substance" of the operation at that level by virtue of the operation disclosing it to us (the oscillation). If mass has momentum without relative velocity, and photons also have momentum, although they lack any mass, there is an more intrinsic quality in common to both mass and energy wave/particles, more basic than either mass or energy, but involved in producing the appearance of both. Clearly, momentum is a more reduced concept than either mass or energy (much to the chagrin of conventional thinking, which came at the problem backwards (for obvious reasons, given the appearances).
Operation is what the traditional understanding of Ki addresses, and all I hope to address.
And yes the nervous system is in play, but sound (oscillation) moves through the body far faster than nerve impulses to the brain (never mind processing time). So the question of how to manage an information flow in that channel with a much slower system of nervous communication suggests that it may be "skipped over" in operation to rely directly on the compression waves for triggering only local muscular action in this mode (Golgi tendon organs and associated reflex channels for instance, which do not suffer the routing delays of cerebellar motor activation).