Yekke2:
Your halachic arguments are, as far as I can tell, unimpeachable. There may be a few niggling points to add/detract, but by and large you have summed it up admirably.
On the moral issue I must take umbrage. From a purely moral standpoint, the abuser deserves to be punished (if we are certain they committed said abuse, of course). We simply believe that in today’s world we have neither the power to punish the abusers ourselves nor the right to give them over to the authorities. The reason we do not is because it is ossur and hakol beyad Hashem. Not because it would in some way impact their family. This argument would be fairer if the abuse in question was only a suspicion.