I say, sue the SEC...the Big 12 Commish already stated that it was okay to accept them. Oh yeah, Beebee emailed the SEC his mistake the night of their voting...last night.
Well, it's not clear that the SEC would win in such a lawsuit. Sure, they had a letter from Beebe which indicated that they were free to accept A&M. But, the question is whether Beebe has the authority to speak or act on behalf of the universities.
Based upon the fact that he is now stating that the SEC needs waivers from each individual school, then I'm assuming each university's contractual relationship with the Big 12 and Beebe does not allow the Big 12 or Beebe to speak for the universities on some issues, such as whether they will waive their right to legal action.
So, essentially, the SEC would have a letter from Beebe, and the SEC would argue that this was a contractual agreement. However, without the authority to act as an agent on behalf of each university, Beebe's "agreement" with the SEC can not be enforced by a court of law.
Of course, all of this is conjecture about the actual terms of the Big 12's agreement with its member universities. Beebe may very well be able to waive the universities' right to sue under their contractual relationship, but I doubt it given Baylor's actions and Beebe's response.