If a lawsuit is purely a mathematical issue for the defendant you are probably right. If it's about finding true liability, I think there is very little, if any on Rad's part, based on what I've heard. I'm not saying what's going to happen with the lawsuit, but I think it ought to be dismissed.
If I were the parents and felt the need to sue someone I think the only appropriate party to sue would be the parents of the other girl, but as noted, Rad has deeper pockets and will likely settle. That's not justice, it's blackmail. But, I don't disagree with your point that that's the way things work.
TT