I have had this discussion with my dub husband way too many times. I do not believe shunning is humane. You say that those who joined agreed to the rules. I joined as a very young adult and still didn't really understand all the rules. What about those born in the confusion and getting dfd just to get out?
Nor did I have a clue that many years later I would disagree with most everything they told me to believe.
I have kids that are dubs and kids out. The ones out tell me it damaged their minds in some ways. The ones that are still dubs think they will live in paradise on earth forever and will never die. Are their minds damaged?
If someone is poison and causes hurt thru pediphelia or rape, these are crimes and should be reported and the proper authorities can investigate. Then people can choose to distance themselves. No announcement is necessary. The news about people gets around.
The other moral choices we make give people a right to choose to associate with us or not. That is an individual right. Never will it be the right of an organization who claims to speak for God.