The Big10 is exclusively schools that are members of the Association of American Universities. Neither FSU nor Clemson are AAU members. The only current AAU members in the ACC are Duke, Georgia Tech, and UNC. SEC members of the AAU are Texas A&M, Florida, Vanderbilt and future SEC member Texas.
They took Nebraska who wasn't and will take which ever school will make them the most money. Naive to think otherwise now.