But if an X user’s note ends up stored on a relay that doesn’t support delete, it’s stuck out there in the wild.
Discussion
That's something they'll have to come to terms with and give users a choice to opt-in. I assume it will a check box. "Participate in Nostr: your Tweets will be sent to Nostr. Please note that doing so, your Tweets on Nostr may not be able to be deleted from all Nostr servers."
I don’t see it happening under the current regime.