Of course, budo is a recurring theme in Take Musu Aiki. It is not gospel, however, and he does admit the possibility of other methods of achieving the same goals.
For that matter, would planning and directing a strategic campaign be classed as budo? It certainly would under the classification of such things in Japan, but does not involve any physical practice...
I think I would read this the same way, were Budo is not a restriction to martial techniques or the practice of martial technique. I think if such a restriction was ever understood to be necessary, there would have been no reason to borrow burgeoning Zen praxis to make martial practice a Way.