But the description is not the thing. For most of human history, there were no descriptions and no explanations of various phenomena in physics terms -- yet bumblebees still flew, and they didn't do so by magic. The fact that a comprehensive explanation isn't available (or, perhaps, just not accessible to a given audience, due to that audience's lack of prior/supporting knowledge) doesn't mean that things happen by magic, or "ki", or some other mystical "it's not physics" force.
There's no way that Mark is saying that it's accomplished through a mystical force (IMO). I think that what he's saying is that it cannot be as simply described by physics as some people represent - or hope.
Anyway, if people hate mystical explanations than I wonder what they think of Ueshiba?