Someone who actually believes this would only delete their copy of the data, and also not turn it over, on principle. That's what the owner of [Lavabit did](https://www.theverge.com/2017/1/22/14350496/secure-email-service-lavabit-relaunches) when the authorities came after him after the Snowden releases. I consider that guy a hero.
Discussion
But it's a moot point anyway since everything on nostr is already in the public domain (except the DMs, I suppose). And relays don't hold nsecs anyway, so it's a non issue.
Nostr is even worse for this than the good old web, because relays are first of all public places and by publishing your notes, with forbidden data that someone can die for, you deprive people of a useful tool (= public relay) where they store their posts about how they poop and what they eat.