The reason it's being taken this far is because there is a chance the SC may rule in their favor. If so, then it's a gained protection for the Church against any such future acts. So it's worth the effort even if they loose.
If they loose nothing will change. The priest still won't say anything for the rest if his life in or outside of jail. If he cares for his soul that is.
However, those people aren't likely to become friends of the Church regardless of the Supreme Court's decision.