"Good money" is money that shows little difference between its nominal value (the face value of the coin) and its commodity value (the value of the metal of which it is made, often precious metals, nickel, or copper). However, it is noted that "good money" is a loose term in modern economics as legal tenders (fiat money, coins, ...) are re-evaluated by the central banks and the market.
If we evaluate the statement from a historical view, cryptocurrency is certainly not a good money since the nominal value of different cryptocurrencies are different. For example, Bitcoin (BTC) is worth around $30,000 USD per coin; Ethereum (ETH) is worth around $2,000 USD per coin (on 31 May 2022). Also, cryptocurrencies are not backed by any physical commodities. That means the gap between the face value (nominal value) and the intrinsic value (commodity value) could be arbitrarily high.
If we evaluate the statement from a modern view, we may consider the properties of money and the functions of money. Cryptocurrency satisfies the 5 properties of money (homogenous, durable, divisible, portable and scarce). However, it cannot function as a medium of exchange, a unit of account, a store of value, and a standard of deferred payment.