“It is halachicly assur for either spouse to litigate in secular court (arkaos) to adjudicate who gets what money, assets, support or custody.”
And only the prenup protects a woman whose husband divorces her in secular court. The form of he prenup that my wife and I signed require us to go to a specific beit din to arbitrate all this. By opposing the prenup you are enabling halachic violations.