The fake @jb55 could still stand up a valid NIP-05 using a different address and then put your domain in the profile. 

That’s why you need the triangulate with the DNS TXT record (in a way, this is a continuation of the argument I’ve been having with nostr:npub180cvv07tjdrrgpa0j7j7tmnyl2yr6yr7l8j4s3evf6u64th6gkwsyjh6w6 for nearly a year except I hadn’t thought of the fake Nostr handle issue until now. )

FYI we met very briefly at Bitcoin 2023 and I was going on about adding NIP-05 npub to DNS then.