They have a right to decide who is in their community.
Everyone agrees on that. That is not the question.
The question is: does the WTBTS have the right to punish people who are no longer members?
The strongest disciplinary process of the WTBTS is the DF/DA/Shunning (all the same one process: announcement+congregational shunning)
the court saw continuing a disciplinary process on a non member to be a violation of their civil rights....
http://church-discipline.blogspot.com/2007/02/mormon-alliance-home-page.html
Excommunication of non members, Norman Hancock
The case of Norman Hancock is an interesting one. It establishes firmly that churches cannot excommunicate members who leave during discipline, based on the Marian Guinn precedent. That once someone quits instantly their legal protections against libel and slander are restored. The state has no authority over the the disciplinary process within the church, but the person has no longer given their consent and this changes things.
The case is standard. In 1985 the Mormon church excommunicated Norman Hancock after he submitted a letter of resignation to the church. Hancock filed an $18 million lawsuit against the church, saying a person has a right to voluntarily resign from a church. The suit was settled out of court. Church representatives agreed to change the records such that there would no longer be any record of an "excommuication": the records would show that he resigned, that is he had asked his name be removed from thechurch role.
http://mormonalliance.org/casereports/volume3/part1/v3p1c05.htm
The JWs try to, and do, get around this by saying DA is not DFing, and that there is no discipline for DA, just an announcement.
But that is not the truth of what they are doing, it is simply a LIE to avoid lawsuits.
Their discipline is shunning, and they require shunning of DA people and DF people.
They are disciplining people who are no longer members and people who don't ever want to be members again. They do not have the right to do that.
(if you read far enough on the "Church Discipline" blog you will see that even the author of that blog fell for the WTBTS lie that there is some difference between the way they discipline DF and DA people. He states that it is understood that JWs have no right to discipline those who no longer wish to be members.)