It doesn't matter about the US military, because the gold market doesn't have to prop up the US military - it gets that ride for free. The point isn't "who is cheaper" in some theoretical sense, it's that as a practical matter the nation of Bitcoinia is importing a large amount of electricity from the USD, RMB, EUR etc economies. This is equivalent in effect to what the gold market as a whole has to pay in storage/holding costs for physical gold. If physical gold holding costs were to rise substantially for some reason, that would significantly reduce the returns available from holding gold.