that this feature is even needed is an indictment against nostr relay norms. there has been options for relay operators to run a relay that actually honors delete messages for over a year now. protonmail has a similar feature with delayed send but it's still my opinion that regardless of the fact that people can cache messages that go out, broadcasting them around when the user deletes is kinda rude. if it's evidence of mischief, then that's good too. personally, i use delete mostly when i make errors and want to correct it. shocking, i know.