I'm not a lawyer, but I don't actually see in the SEC 2017-2018 bylaws where Sankey can deny a school from making a hire. Consult with yes, but actual denying a school from making a hire I don't see.
19.8.1.2 Hiring Practices. Member institutions shall exercise best efforts to hire individuals committed to rules compliance. In connection with this requirement, member institutions shall thoroughly evaluate an individual’s record of rules compliance prior to offering employment for any coaching position or noncoaching position with sport-specific responsibilities. While each member institution makes its own hiring decisions, member institutions shall, at a minimum, request specific information from each candidate concerning his/her rules compliance record and communicate with NCAA enforcement and the Conference office regarding the same prior to offering employment to any candidate. In addition, where a member institution considers hiring an individual who has engaged in unethical conduct as defined under NCAA Bylaws or who has participated in activity that resulted, or may result, in a Level I, Level II or major infraction, the President or Chancellor of that member institution is expected to consult directly with the Commissioner prior to offering employment to the individual. Each member institution must include in each contract with every athletic director, coach, senior woman administrator, and other employee of its athletic department a specific provision obligating the employee to comply with the Rules and specifying that the employee agrees to be bound by and will comply with the enforcement, penalty, and other disciplinary provisions and procedures of the NCAA and of the Conference, including but not limited to the provisions of Article 4 of the Constitution and of this Bylaw 19.8.