my sifu has an indirect relationship to this system;
perhaps, but I think that he is also buying into / perpetuating a particular conceit on the part of "internalists", who seem to have this need to characterize what they do as being above such base methods as using muscle power - it's one that has rather deep roots, unfortunately; and I have experienced it before elsewhere; problem is, they can be clueless about anatomy and kinesiology: for example one person I knew, very high level bagua, tried to make his point about not using muscle power by having me feel his tricep while he held his arm out extended at 90˚ from his torso - he was like "look, no muscle power"; of course, I didn't have the heart to tell him that triceps have nothing to do with holding the arm out that way one it is already extended - but I suspect he was showing what he had been shown by his sifu...
anyway, I don't think that, just because they demonstrate skill in their given area of expertise that it should make an allowance for him being intellectually sloppy in another area - consider the inverse: someone with expert knowledge of neuromuscular physiology drawing incorrect conclusions about "internal" practice - how forgiving would you be of that...sword cuts both ways...the interesting thing then is, what happens when you come across someone high-level competent in both areas...
IMPE, one can talk about it all day and even reveal the "secrets" if one wanted to, but the reality is that the only way to really "get it" is to a) feel it; b) train it; but this is the case with most anything involving subjective skill; I personally think that it has more to do with keeping one's rice bowl intact...
IMPO, the body is the body, and nature functions according to the principle of regression towards the mean...