I have not yet read the posted article...
I could see this becoming legal from the stance of promoting hate. The protected class that could pursue this would be the LGBTQ community. From those foundational arguments, it isn't a stretch to say that ALL shunning is religious persecution since people are either choosing another religion, or choosing to believe something else entirely. It is also true that the JWs could be seen as interfering with an individual's right of freedom of assembly and association since individuals are not free to join or leave a group without social consequence.