This is a statement just released from the SEC:
Statement from Dr. Bernie Machen, Chair, Southeastern Conference Presidents and Chancellors:
After receiving unanimous written assurance from the Big 12 on September 2 that the Southeastern Conference was free to accept Texas A&M to join as a new member, the presidents and chancellors of the SEC met last night with the intention of accepting the application of Texas A&M to be the newest member of the SEC. We were notified yesterday afternoon that at least one Big 12 institution had withdrawn its previous consent and was considering legal action. The SEC has stated that to consider an institution for membership, there must be no contractual hindrances to its departure. The SEC voted unanimously to accept Texas A&M University as a member upon receiving acceptable reconfirmation that the Big 12 and its members have reaffirmed the letter dated September 2, 2011. [my emphasis]
Word is that Baylor is the institution referred to in the boldface above. What the SEC appears to be saying is that unless all parties in the Big 12 are on board, it will not accept Texas A&M into the league. That could be a wrong reading, as there is no explicit language to that effect, but it is suggested by the last sentence.
I am not a lawyer and I will not comment on the grounds under which Baylor may sue. Whether or not they have any real chance of success, an actual lawsuit by Baylor would seem to delay the process months or even years, unless they can be talked out of it.
Gary Parrish congratulates Baylor for doing this, although I have no clear idea why he thinks that Baylor should be congratulated. I am not a proponent of conference realignment, but it's hard to imagine that Baylor can stop TAMU from legally ending its association with the Big 12 and prevent them from joining the SEC by threatening to sue.
Baylor could have plenty of suitors for other conferences, should the Big 12 break into bits and the pieces go elsewhere. It may not be as prestigious as the SEC or even the Big 12, but it seems to me that suing the SEC is a real "Hail Mary" unless the SEC and Texas A&M fear losing. More likely the concern is a fear of losing in the public relations battle at the moment, but I can't really say.
If the SEC decides to let TAMU and Baylor fight it out, what we will presumably see is some kind of process in the Big 12. It doesn't seem likely that Baylor's lone "no" vote can permit the lawful withdrawal of a member, but I have no idea if that is true or not, it depends on what the contract says. It was my understanding that Texas A&M was attempting to do just that, but unanimous consent may be required for all I know.
What the SEC seems to be saying is that it would rather wait and see what TAMU does to make a Baylor suit moot before allowing them to join. So for the moment, at least, SEC expansion is on hold.