By treating this girl's confession with exactly the same confidentiality he treated everyone else's confession?
It doesn't matter. This is a non-negotiable for us. You can put every priest in the US in prison for life if you wish, "compelling state interest" be d-mned.
So now your position is: whatever the law is, it really doesn't matter. Priests have the right to give bad advice to penitents [advice which is contrary to both the law and their own morality] and damn whatever the law is, because your church has a Constitutional right to protect molesters.
Yes, the Church of Rome has always taken that position, and it is paying dearly for it.