Dwise did reply to my original question that he didn't know for sure ''Ki'' was supernatural of not, if I'm not mistaken. It's still somewhat vague what he actually believes.
Perhaps some modern teachers do know about the biological limits being fully used, and the physics involved, others may not. Especially when spiritual beliefs are still being held, a combination may be common, I think, I have no knowledge on the subject, so I cannot say, it's just speculation.
But Ki seems pretty handy for visualizing in your mind, and so it provides a easier way to learn things, even when not knowing the science. My gym teacher told my class once that mental visualization can really affect your performance, so it's not really trickery, as long you learn real material arts, no bogus. A dependable teacher, in my mind, would either just stick to it as a metaphor, or really hold some traditional beliefs, which may not exactly represent reality, but unlike faith healing, it's still not teaching a full lie.
However, like Panda said, mystical Ki/Qui/other master on tv pulling all sorts of miracles..have a pretty high chance of either have some unique body ability they don't fully understand(think snake people, testicle pulling hole in the muscles), or are indeed tricking people, or both.
Still, in general, is it really needed to be so tense? Perhaps Dwise can give us a rating about (super)natural Ki on the Dawkins scale, can we can all be sure of his ideas beyond any doubt. In the case of supernatural sources, I'm curious how it ever did evolve in animals, but once again, Dwise seemed to accept either possiblity.