Should the defamation fall outside the listed constraints, then it becomes a battle of the lawyers, should they decide to waste each others money. Otherwise, all they can do is to publically refute the defamation. Hell, the rats do it all the time. Meanwhile, the little guys who cannot afford to waste money on litigation have the web and other media sources to hopefully support their position. I think loser should pay, no matter the chilling effect it might have.
Kasich is such a joke as a presidential candidate anyway that it is obvious he is doing the bidding of his GOPe masters here.