I don't think there are substantial merits here.
I'll put this into simple terms.
Until now, the ACC has succeeded in "keeping the ESPN deal secret" from the public (I think the GOR was published fairly soon after it was entered into, but it doesn't have a lot of "sensitive information" in it).
Of course, the ACC (and any P4 conference) is made up of more than half "public institutions", many of them in states which have versions of the Sunshine Law and/or other forms of public disclosure laws.
So from a STATE perspective, a legislator (or citizen) would say "why am I able to get information about my institution towards which I pay tax, but then SUDDENLY a conference negotiating a contract on behalf of my institution says 'nope, you can't see this contract'", and I very much understand and sympathize with that argument. Essentially, one could argue that a school could "use" a conference to shield information from the general public, simply by shifting some of its contracts to the "conference level" and then agreeing to secrecy and non-disclosure clauses.
This is particularly true when the ESPN TV contract is not nearly as sensitive as, say, the research of a professor who is working on a cure for cancer. Or the guidance system for a Star-Wars type laser weapon (kudos to the great 1985 film "Real Genius"). Instead, the only "sensitive" information in the document is how much ESPN is willing to pay the ACC (and the member schools).
And I can't imagine a judge would NOT think that this information is EXACTLY the kind of information that states intended to be discoverable when they passed public-disclosure laws.
In conclusion, I will reiterate what I have said all along (and my apologies in advance to any of the idiots who actually believed one single word that
@NorthernVirginiaCane typed), but you can put ANYTHING YOU WANT into a contract. And anyone can sign it. And anyone can follow it, for a while. But NONE OF THAT means that you can never challenge those provisions in court as unenforceable. And I tend to think that the "secrecy" clauses the ACC drafted will not survive a legal challenge.