Well, when Utah threatened suit via Orin Hatch, Utah certainly wasn't blackballed or locked out in retaliation. In fact the opposite occurred with a reward of a PAC invite. If P-5 didn't think Orin Hatch's suit talk had validity, they would have never rewarded Utah. So, SMU leading the charge in terms of threatening suit in my opinion isn't going to screw SMU.
In any event, I just don't see a scenario where the big Universities are sued by roughly 60 schools and lose. Can't lobby the Supreme Court. And as far as legislation, just count the senators in States with D-1 schools who are left out versus the State senators that have schools in the p-5.