Joseph, I’ll tell you what would be kangaroo justice (besides for the NYC traffic court system). If the law of the land were relaxed when the accused belonged to a certain group, that would be kangaroo justice. Just because a person belongs to a certain clan, they cannot be exempted from the rules that govern all citizens of the country, even if the clan promises to discipline and resolve the problem internally.
By what reasoning should this mother be treated any differently from any other mother suspected of abusing her child? She is not being singled out for any unusual discipline.