Indeed, timestamps are really useful in nostr notes. 

I agree that inconsistency is often undesirable, though I'm hesitant about concluding that relays should coordinate. It's my nostr client's job to ensure that the content is consistent across all the relays that I use. Perhaps I should be using fewer relays if I'm unable to maintain sufficient consistency across all my relays. It's enough to have just one relay with the outbox model 😀

I realize the UX suffers from having all the business logic in the client, but where do we draw the line between Twitter and nostr if our relays keep getting smarter? 

 Short answer: relays dont get smarter, clients do.  You provide the proof in a tag, and it can be verified by the cllient.  The client knows when a profile is the latest, and when it is stale, that's about it.  This also opens the door for other use cases, other than profiles. 

 Wow neat!
Apologies for my premature comments and thanks for explaining 😀