I wouldn’t be so sure about that, unless you are equally convicted in that court’s jurisdiction’s conviction to outright ban the whole chain from use - because as soon as two courts mandate two different forks, one of them will be banning a chain that the rest of the globe has consensus on. It’s a lot like banning a whole region from sending mail because one person in that region got caught mailing drugs.
Here we are talking about the hypothetical situation of the U.S claiming complete jurisdiction of Ethereum. The U.S could make whatever laws it likes around the usage of Ethereum, legislate that all nodes have to adhere to these laws and job is done. The rest of the world can say "lolbye" and continue using it like nothing has happened, but in the U.S they would likely have to fork and create a new chain, and those who want to use it legally in the U.S would also have to use this new U.S-regulated chain. From there they can then implement processes to reverse transactions, introduce identification requirements etc.
When your protocol’s primary use case relies on denominating centralized currency, it makes these types of network attacks far, far more effective when the attacker controls that currency. People have completely forgotten about any use case of a non-excludable censorship resistant network that isn’t tokens, but I digress.