This article distinguishes currency, for which that is true, from money, for which it is not. It is an idiosyncratic definition, but it is the one this article uses.
I think ultimately it's a useless distinction. People try to argue about "sound money" and all that, but more and more my view is that both the historical/anthropological evidence and the realities of our modern economic systems point towards the debt as money theory, and that sound money just doesn't really exist. Commodities like gold are commodities, and currency (which is money) is different.
