Anyone (or group) is free to shun anyone (or group) as they wish.
As long as you remain a member of a group that practices religiously mandated shunning - you are obliged to accept your cults ecclesiastic authority to both shun and to be shunned in accordance with the dogma you yourself support as a member.
The mistake JWs make is not quietly quitting the cult in advance of the cults judicial actions requiring the members participation in such distasteful acts. You join the Nazi party - you are obligated to act like a Nazi.
A judicial committee cannot be formed in respect to a former member. And you are legally free to quit any religion at any time you chose.
Stop making targets of yourselves - quit the f-----g cult now. Make a written record of the date to show the hounders when they finally track you down - they have no authority over you unless you grant it to them.