The commissioner isnt some all powerful figure. The commish can only act within the wishes of his membership. When the membership is fractured, the commish can present options (as he did last year, which kept the conference limping along for another year), but ultimately everything rests on the shoulders of the members of the conference, particularly those members with power in the conference.
As I pointed out, he's the leagues head administrator. He should have formalized, in writing, what the remaining 10 schools committed to last year. It was stated there would be stiffer penalty for exit after NU/CU left. By all accounts this year, the same by-laws were reviewed to determine the exit of A&M, that was not what was stated after the loss of NU/CU. He should be fired for not doing his job to protect the interests of those remaining...