Once his parents let others take his picture they lost all rights to privacy in regard to the pictures.
The pictures became property of the takers.
His parents were far from having any moral standards by involving their child in the crime.
Your kid and your permission have nothing to do with this case.
You are implying that all parents are aware and consenting of all photos that are taken of their children. Do you really think this is true? What if someone was taking bathroom pictures of your children with a hidden camera? Do you and your children have no rights to privacy because the photos belong to the taker in this case?