I don't doubt that there are military applications to shuttle flights. After all, when the shuttle's going up anyway, why not put some military stuff aboard. That would make sense.
But to say that the shuttle flights are a PREREQUISITE to US military supremacy in orbit, is wrong. In my opinion.
Well, since we currently have no other manned military access to orbit, I dont think we can afford to view China's ambitions to get into space as entirely commercial.
I recall a statement some time back of an Air Force General, whose name I cant recall, to the effect that, "We must not only be prepared to fight in space. We must also be prepared to fight our way into space."
There's a certian ominousness in that, which informs the opposite of your view, to me, as much as I respect it, however.