The point that the author was making has to do with the fundamental capacity of crypto to be classified as currency.

You CAN store it, you can exchange it for goods and services and you can quote prices in it.

Adoption and price gyrations, while important, are exogenous to the issue of classification and largely depend on your base currency willingness of the government to accept crypto (with Japan being the most advanced in this realm).

Note that by your standards the more volatile currencies (e.g. Veneselan bolivar) aren't really money...

Compared to the bolivar Bitcoin is a pretty stable and easily accessible alternative.