Earlier quoted context omitted.
If it's actually on chain as a smart contract, it can't be shut down unless the code was written to allow it.
You could make hosting and distribution of the code a prohibited act. Wanna still host that Blockchain if it can get you arrested? Just cus it lives as code doesn't mean someone or some group isn't responsible for distributing it.
And there goes the blockchain.
I'm shocked it hasn't happened already given the fact that many popular blockchains allegedly host illegal images in the transaction metadata. That's all the FBI needs.
The only reason I can imagine is that blockchain and crypto are still useful to people in certain positions. Exfiltrating money from foreign regimes, etc.