Child abouse != assault of a child.
I believe what Sand meant was that we have to try and figure out, if possible, whether the child is actually aware of what he did. It is commonly accepted in modern society that children aren't accepted as fully grown until a certain age, usually 18.
I have no idea how anyone could figure out whether he knew what he was doing and was capable of comprehending it, but that should be the first thing that any authority should try to do.
This is obviously slightly "pie in the sky" stuff, but shouldn't be dismissed out of hand either. I'm actually surprised at how much I agree with Sand here, children are different than adults and that should always be taken into account when handling them.