I've had a theory that whenever a hard fork occurs, it is up to consumers to decide which side will succeed by selling one side and buying the other. But I had assumed that hard forks would only originate from private groups; I hadn't considered that nation-states (or a group of nation-states) might start a hard fork.

For "compliant Bitcoin" forks to work, two things would need to be setup prior to the fork:

Implementing those two requirements will be very difficult. Thankfully, most nation-states are not capable of such coordination. But the IMF has many smart people; the IMF might be able to get a few European countries to implement the two above requirements. But we shall see.

Without the above two requirements, consumers will be able to curb-stomp the "compliant BTC" fork by simply choosing what they think is the better option. And since a "compliant BTC" fork will obviously be worse than BTC, most people will assuredly sell the former and buy the latter. Those who do the opposite (every transaction has a seller and a buyer), will ultimately be poorer as a result. In other words, hard-forks transfer wealth from gullible people (those who like the inferior side of the fork) to the cognizant people (those who prefer the superior side of the fork).

In this way, "compliant BTC" forks are self-defeating, because they punish the compliant people and reward the non-compliant people.

This is a likely outcome, but it is not a guaranteed outcome. There is a possibility that some clever academic could discover a way to trick people into buying "compliant BTC" and selling BTC. I am not sure how such a trick could be arranged without outright defrauding people. Mass fraud would lead to runs on centralized exchanges, which are the primary (only?) vehicle for state-control of cryptocurrencies. But that would be good for Bitcoin, because shitcoins can't survive without centralized exchanges.