Alexander Technique is one somatic technique of many. All of them lead to skillful movement and without background knowledge there no reason to assume that a specific technique inspired Dune.

I was guessing based on timing, but looking into Herbert I'm not seeing any obvious influence. It's more a statement of Dune's impact on how I think about movement than it is about Herbert, it looks like.

I don't think that discussing it is inherently impossible. It just hard.

Well, you can certainly elaborate the basic intellectual edifice, as done for Zen here. My stab at it:

Humans are 'psychophysical systems' (read this as a rejection of dualism in practice rather than just philosophy). Most people don't use themselves skillfully. One of the key skills in using yourself skillfully is learning the skill of not doing habitual wasteful or harmful actions, and this entails unlearning habits and defaults.

The sort of person who reads LW probably has significant experience entering strange new conceptual territory, to wrap their mind around beliefs or opinions that seem totally alien to them; they probably don't have significant experience entering strange new physical territory, in the sense of moving or keeping their body in a manner that seems totally alien to them. And just as concepts that start off seeming alien can turn out to be helpful and grow familiar, so can physical mannerisms.

Communicating concepts in words is difficult but mostly doable. Communicating mannerisms in words is many times more difficult, and illusions of transparency even worse. Communicating mannerisms by touch is difficult but mostly doable. The communication difficulty is increased by the fact that the 'mannerism' involves the level of tension in the muscles and resistance to movement as well as the position of the joints. (I can show you a picture of how my shoulder is oriented; can I show you a picture of how readily it moves when you push or pull my hand?) Note also that many people spend years of focused effort in learning how to better communicate with words (both listening/reading and speaking/writing), and very little focused effort in learning how to better communicate with mannerisms (observing with sight or touch and demonstrating with example or touch).

It's even more hard when the people you are talking with don't have the background to understand the basic claims and then want peer reviewed research for every claim.

There seems to be a general heuristic of "if you can't articulate how you know X, I don't believe that you know X" that I am deeply ambivalent about using. On the one hand, it serves as an impetus to abstract and formalize knowledge and is useful as a cautionary principle against trickery. On the other hand, much (if not most!) knowledge cannot be easily articulated because it is stored in the form of muscle memory or network associations rather than clear logical links. I don't seem to rely on that heuristic very much, for reasons I haven't fully unpacked.