If the only item within the lawsuit was that the option was extended then yes, your point would have some merit. The lawsuit appears to be throwing a number of perceived grievances our, hoping that something sticks.
Were they fighting to keep it from their members or from the general public? I seem to remember reading that the member schools were allowed to view the documents in the ACC office, they just weren't allowed to take copies back with them. I also seem to remember the judge in Florida ruling that FSU was allowed to receive a copy but they could not share it with outside parties, could not publicly comment on its contents and were required to destroy the document once they finished reviewing it.
Back to the commissioner and whether he does or does not have the authority to extend an option, operating agreements, management agreements and employment agreements would all be accessible to all members. I know exactly what would happen if I signed a contract as a representative of my firm. I am very confident that ESPN, the commissioner and senior representatives of all ACC member schools knew what the commissioner did and did not have the authority to authorize at the time the extension was agreed to.