It shouldn't be surprising that this happens again and again, and they only need to succeed once. Social movements of the past understood this well. They increased the costs to such an extent that they couldn't be ignored.
Look at the movements that brought forth societal change in the past and imitate them. I can't think of one that didn't have an "extremist" wing that was willing to target the decision makers were it hurt: economic output (eg. strikes or sabotage) and violence.
If so, that is the real solution, because it works in all cases.
Not sure any purely wireless system would scale that well either since every message floods the entire network. Ideally for wireless you just want wireless to the closest grid connected node to connect to the internet.
Encrypt your data locally before it is uploaded to a service that scans your private communication. This is most likely how the child abusers will do it too. And therefore the law will be ineffective at fighting sharing of child abuse material on the internet.