Its hard to mandate that a sex offender be announced to a congregation during meeting obviously. However upon even one "witness" or victim of abuse (NOT 2), there should be a reporting to the police as well as informing ALL elders and MS in a private meeting that Brother Raper has been accused and should be treated as if he is dangerous around children with respect to assigning him in car groups. In fact making it a policy to only assign him to a car group with an elder or someone informed would be the best.
I agree cappytan that it is the moral obligation to forewarn any parents whos children might come in contact with Brother Raper in service. Actually informing all parents might be necessary to help lower risk of something happening at a get-together or at one of those "lets watch this new WT video just released at my house as a party" type scenario. Or those big camping trips some JW groups have. Theres simply too many scenarios where not informing parents could fall back on a failure of Elders moral obligation. Protecting young sheep should outweigh protecting the reputation of some sick f***. Perhaps give Brother Raper the ultimatum of 1) no attendance at any gatherings outside the Hall whatsoever and limited field service partners to elders only or 2) we announce you as an "accused" or "confirmed" sex offender to all parents we elders see fit in order to protect the cong to the best of our abilities .
Yea that sounds good, JWs love ultimatums anyway, should work fine.