Since what they did was extremely and completely wrong, they deserve an eye for an eye kind of justice, where if a family kills a child, the family gets killed for the most evil crime and perfect crime of the 21st century. Enough said, yes it is justified. Yes yes.
Because families literally ate their own children after they slaughtered them for not believing in Christmas. They killed children, why wouldn't there be justice for these children by killing entire families and saving the child, also maybe take the child to a counseling center to retain mental stamina from traumatization.