the damus relay now supports NIP-70 protected events:

if you really don't want people syncing your notes to the damus relay, just add a `-` as the first tag.

https://github.com/nostr-protocol/nips/blob/protected-events-tag/70.md

nostril --envelope --content hi --tags '[["-"]]' | nostcat wss://relay.damus.io

["OK","cfd281d9199bfbdfe1b9f19513b8b83211b2b2dbbe58fc80297a52d6d5b846e9",false,"blocked: event marked as protected"]