People need to step back and picture a world where the government can come and tell everyone who they have to talk to and do business with. How would that work? What kind of a world would it be?
This is exactly what some religions like the Mormons, JWs, Scientology, etc. do. They do this by ENFORCING shunning. That is, shunning those who do not respect their shunning decree.
The court ruled as a precedent that it is not for civil courts to interfere with the internal operations including discipline of its members and who they choose to allow to be members.
... As long as that discipline stays within the boundaries of that religion. The ultimate discipline being outcast out of the group. Shunning does step outside of the religion by inflicting emotional abuse on someone that is no longer a member. They don't have the right to "discipline" people who are no longer part of their group.
Supreme Court needs to review the practice of Shunning organized by the religion. We cannot force people to talk to people. However, we can act against people who do force people NOT to talk to others.