Earlier quoted context omitted.
To which I would of course reply that they are not money ;)
To which I would reply that money is defined by three properties: 1. Store of Value 2. Unit of Account 3. Medium of Exchange Of which it's fair to say that several crypto currencies fit that bill.
If you want to think of it as a unit of account, it has to be a state unit of account in order to actually function as money.
And finally I think that the function of money as a medium of exchange is actually a side effect; that is to say that money is the most liquid asset because it is created by an obligation in common to all citizens of a sovereign entity. As such, it is the most likely medium of exchange because it is universally accepted.
However, anything can be a medium of exchange. Hot rocks can be used to heat a room, but you wouldn't call a pile of hot rocks a heater. In the same way, virtually anything can be a medium of exchange, but money (by virtue of being created by the imposition of a tax liability) is the most effective medium of exchange.
My definition of money is: a credit that can be used to extinguish a tax liability imposed by a sovereign. Everything else is a commodity.