I suspect Rothbard had an intention, which was to stress his opposition to fractional reserve banking. He knows that one of specie’s strengths is its limited physical supply and that because of this the supply of gold is relatively stable. This reminds of George Orwell, except this time it’s Rothbard using the vague language to push an agenda. The debate over whether the Austrian definition of inflation is different and more/less useful, in my opinion, is not only a debate over a non-existent difference, but fails to address actual changes in the definition, such as this one, that clearly suffer from a narrow vision.That is Jonathan Finegold-Catalan discussing Murray Rothbard's definition of inflation from Man, Economy, and State.
This kind of weird language is precisely what puts me off of Rothbard. In some cases, it feels like he's being deceptive. In other cases, it feels like he doesn't know what he's saying. His work is generally pretty smart, so I am reluctant to accept the second possibility. But the first possibility is potentially much uglier.