If they made a truncated hash of the npub bytes, the first 33 can be represented by 3 words from the BIP39 word list. This would make impersonation a lot more difficult. It should show prominently on the profile underneath the user-configurable fields with a bright note saying "if this is not what you usually see this could be an impersonator".
Discussion
33 bits I mean. BIP39 words there is 2048 of them and each represents 11 bits. 3 words represents roughly 8 billion, and due to the properties of hash functions, this would never collide with up to about 2 billion users.