That involves that every single relay implementation available on the internet should include your pubkey on a black list. And if that's even possible, you can always run your own.

That persona non grata would alway find a relay that doesn't block him. If he's a nobody, any random relay would have him. If he's Satan himself, he still will have worshipper that gladly host his notes. There's truly no influencer that would get shunned by all the world.