e2e encryption is in danger as is, and the strongest arguments against both are rooted in the same ideological substrate (criminals vs those needing protection); as are the arguments in favor.
If you ask the government to prevent the use of cryptography in cryptocurrencies then you undermine the argument that the government should not tap or intermediate all communications.
At the end of the day, a financial transaction IS a message. It’s a command to a ledger to make an adjustment.
I am just arguing against public blockchains, resulting in a very specific, wasteful, and unregulated form of digital money.
I'm specifically asking for a legal theory, not a political framing, because your explicit mention of the Supreme Court implies a scenario where politics will ban/regulate one of both things, and then courts will employ the "money is speech" argument to map the ban/regulation of that one thing onto the other thing.
This is my line of reasoning. Whether he dislikes cryptocurrency or not is irrelevant, but the argument that you cannot have a safe system with private credentials was what I found objectionable.
EDIT: Re legal theory: The idea that cryptographic systems are unsafe is likely to result in a weakening of protections for such systems. Cryptocurrency is an easy target because it’s essentially 100% cryptography and because it has no patron. The banning on cryptocurrencies can be extended to a ban on private keys via the safety argument.
Closest analogue might be gun control (Encryption is legally considered a munition).
Last edit, I promise: this creates a situation where a cryptocurrency wallet is simultaneously a munition (2nd amendment), speech (1st amendment), and secure papers (4th). Legislators could use this nexus to move between domains to expand the scope of any bans.