I like the idea of creating an npub for each Usenet account and publishing those posts, maybe even backdated. I don't think you could transfer an account to a person that claims it though because there's no way to transfer a private key beyond being shared with the archive service.
Discussion
That said, split zaps are a thing so practically it would work out fine if the idea is to receive zaps for your old Usenet gems lol
I would have no way of verifying my old posts, other than the coincidence of a shared name. For anonymous NOSTR users that would be near impossible.
I don’t rate that as an important function however. I’d just like a historical record.
I agree that we couldn't give the nsec key to anyone, unless they are still using the original email address used to make the usenet post. Maybe not even then. But even if nobody could claim them, they should still be accessible.