I understand the decision. The impact would be too big if it would be forbidden. Jewish organizations will appeal as others, incl. Non-religious organizations.
It's difficult to define a general definition of shunning. In my view, it might help to apply the same practice to JW's. Shun them where possible so they can experience the impact themselves.
The bad practice in WT land is that the leaders want to enforce their shunning practices on all its members and there are consequences if you do not comply. It therefore becomes an enforced practice and not a voluntary application of the practice. But very hard to use this in a court case.
The peculiar thing is the shunning is not something that Jesus instructed. It's a human practice to protect their own interest. Create a short movie (like the one shown during a convention about not responding to a text message) and share on social media. It will have far more impact and not illegal.