Baylor's trying to save its ass. If the Big 12 disintegrates, they and the other leftovers are going to get dumped into the WAC or Mountain West or Big East, while OU, OSU and UT go to the Pac 16. Waco to Mansfield, CT for a conference game? Not an appealing prospect.
The lion's share of the blame for the Big 12's problem's has to be laid at the feet of Texas and the Big 12 office. By doling out uneven shares of the conference revenue they've left many of the teams economic second-class citizens. It's no surprise Nebraska, Colorado, and A&M are headed for what they see as greener pastures after being lorded over by the Longhorns.
I don't particularly want expansion, Twelve has worked out great for the SEC. In any case, the move to 16-team super-conferences is inevitable and it's best to get while the getting's good. There are a number of connections between A&M and the SEC. Bryant, Stallings and Sherill coached there with Bebes being on the Board of Regents so Alabama fans have an affinity for them. They were a long-time rival of LSU and Arkansas so those series would be revived. Of all the possible remaining Big 12 schools, A&M makes the best fit with the SEC.