No one 'leaves' the JW's since they claim to have loyalty to anyone for life who remains in good standing with them. A person may be asked to leave under 'apostate' status, but the JW's certainly don't miss an opportunity to have a celebrity encouraging their growth, unless he has been accused of child abuse, then they turn tail and run because the leadership doesn't want the upside of fame to be offset by its downsides. When it happens in the Catholic Church, the leadership defends the accused and follows the protocols Christ gave us for dealing with sins and accusations within the Church, (Matthew 18:15-18). They do not include going to an evil secular world for 'justice' or abandoning and betraying your own people to make yourself seem more righteous, particularly since the 'secular' world is the source of the problem, with 12.5 million cases of child sex abuse per year, most going unreported because reporters fear the organized criminals behind this evil. They do not fear attacking the Church quite as much.
Noticeably absent from Michael Jackson's trials were any supportive members of the JW's. They do not even support him after he was acquitted on all counts. They also didn't return his vast monetary contributions to help with his legal defense fund, even though he was financially struggling at the time.
Would you stay among people who treated you this way?