It probably won't help find William but sometimes adjacent issues have to be addressed when something as horrible as this happens.
I think we should think deeply about the issues of stigma and not just go for the bandaid solution. Convicted offenders get to maintain anonymity depending on who they abuse. Think about the ramifications of that. I have always wondered, if it was Bill Spedding who abducted William, if William's foster status did contribute to his decision to do that. Not because of the legal ramifications (because he had no intention of being caught) but because in his experience, foster children are not truly valued by either their biological nor foster parents, and perhaps to him, in his worldview, William was seen as disposable.
No one likes to say it but not all children are cherished, protected and wanted. Sometimes when people lose their children to foster care they do not put up much of a fight. People have personality disorders, addictions, dysfunction. Sometimes it suits them better to make themselves out as victims, than do the actual hard work of getting themselves on track and parenting well.
And there is also a contingent of people prepared to foster because they don't assume all the burdens of good parenting or they see it as a way to have their own needs met, dark needs, not the normal every day need many people experience to nurture and love a child.
In amongst this are people who perhaps had children at the wrong time and do have it in them to do what's required in a better circumstance, and others who recognise their own limitations and support their children finding a stable family, and people who see fostering as an amazing privilege to expand their family. It would be a much better world if this was the case across the board. As it appears, KT seems to be doing well now as a parent and William's foster family seemed to be a good one. Hopefully the foster situation had nothing to do with what happened to William.
If nothing else, this decision has shown that how we go about these issues is up for debate. There is no doubt we need to do better by our children.