I was thinking some more about the nature of measures and money as measure. One of the things that came back to me was William Wallace, OP’s writing here. In order to be a measure, the law must be homogeneous with what it measures, that is the same in some way. In order for a law to be a rule and measure of justice, it must in someway contain justice. In this sense, an unjust law is no law at all, because injustice as a lack of justice is a nothing and a nothing cannot be a measure.
Extend this further to other measures. Try using an atom at 0 Kelvin to measure the Olympics. Use a point to measure a line. Use a thought to measure the mass of an object. Use a syllogism to measure a distance. Something that lacks a the property to be measured cannot be a measure of that property.
In this sense, it is very true that BitCoins cannot be money, because they have no value or are at most nearly worthless. Indeed, to say that money as such is intrinsically worthless is to entirely miss to purpose of money. Money must be something with value in order to be a measure against which incommensurate things are compared.