They were part of a conference with TAMU. Among the legal ramifications, they all share a TV deal. They have legal grounds to sue TAMU for leaving the conference. As I noted earlier, each school is realistically only due 1/9 of whatever fee conference members have to pay to leave the league. Since Colorado and Nebraska had to pay nothing, unless they changed the legal wording on the new charter, Baylor et al are each due 1/9 of nothing.
The league would have had legal recourse against the SEC for tampering if they had accepted TAMU's first request, before the Aggies had withdrawn from the B12. The SEC's policy is not to accept any team unless it is clear of legal entanglements - that is really what is holding up this deal. The SEC doesn't know how this infighting will shake itself out so they have not formally accepted TAMU.