My dearest darling; I doubt that Amkor wants to risk an arbitration award "in excess of $125 million." (And when Tessera says that, I think the number they are projecting is a few times 125, not a few more than it). I doubt very much that Amkor are being obedient children and paying the minimum possible amount immediately in hope that their polite behavior will lighten the total penalty. Whatever is going on, Amkor is trying to put a cap on their penalty, or if not to cap it, to delay it.
We are indeed fortunate, in view of Tessera's developing non-communication policy, that a few words more than the barest minimum were included in the press release.