Thank you for proving my point!
Ribbons are property of the U.S. Armed Forces and Congress can stipulate conditions for using them!
By "property" I meant "real property." I though this was apparent from context since I was referring to clause 17, which covers "...authority over all places purchased...", but perhaps I should have been more precise in my language.
Military ribbons are things, not places. Moreover, the Federal government does not "own" ribbons purchased by private individuals from private sellers.