No court in the developed world is going to order citizens to forcibly associate with people whom they do not wish. I'd have to read the actual legal documents to figure out what's going on, but I'm absolutely confident that that's not it.
I don't see a way for governments to stop religious shunning without committing extreme human rights violations along the way. The best they can do is strip religions that cause grave harm to their members, and ex-members, of all special protections and privileges.
I've heard the argument before that Watchtower is guilty of incitement to hatred against former members. That may be true, but hatred isn't a crime, and incitement to something that isn't a crime isn't a crime [sic].
Civil claims under tort law may be in order, but I don't think that "____ is no longer one of Jehovah's Witnesses" holds up under the legal charge of slander, even if we all know what it REALLY means. They deliberately word things in a certain way to avoid getting bitten by it later.