any note suspected of being shadow banned would just get blasted to more relays. its kind of nonsense. its really hard to stop notes from replicating everywhere. the protocol explicitly supports it.
Discussion
apart from the fact that if everyone manages their own relay, it is more difficult to delete the publications
also all damus nodes store the note locally, you could build a p2p overlay network that asks for specific note ids if they couldn't find it. then any node could help out