"I'm not sure of anything that they could have done differently." Disfellowshipping merely expels him from the JW community, but leaves him entirely free to menace the community at large.
What about the danger he poses to non JW children in his neighborhood? Or is their welfare none of our concern since they're going to be annihilated anyway by the Bronze Age tribal desert God of the Hebrews?
Let's review: Child abuse is NOT just a sin: It's a CRIME!!