They were trying to pressure Texas and OU into leaving and break up the Big 12. By making a public announcement, they were telling the rest of the Big 12 that their conference was unstable. They were trying to tell OU to join the PAC 12 before the Big 12 fell apart and Texas left them high and dry.

It didn't work out for the PAC 12, but it did get Colorado, Texas A&M, Missouri and Nebraska to leave. Only Colorado went to the PAC 12, but they certainly diminished the Big 12.