First off, The pre-nup has the endorcment of Rabbis Zalman Nechemia Goldberg, Dov Schwartz and Moshe Heinemann, who I do not believe are MO.
Rabbi Gedalia Dov Shwartz is definitely MO. You seem to assume that just because he is a talmid chochom and a well regarded posek, he must not be MO.
Matan, you may not agree with MO on everything, but this is way over the line.