Setting aside the exit fee, the issue in this action (as opposed to the FSU suit), isn’t whether the GOR is binding, it is a question of what the GOR actually covers. The GOR says each member grants to the ACC "all rights ... necessary for the Conference to perform the contractual obligations of the Conference expressly set forth in the ESPN Agreement, regardless of whether such Member Institution remains a member of the Conference during the entirety of the Term."
Clemson's argument is that rights to games played when a school is no longer a member of the ACC are not "necessary for the Conference to perform" its obligations under the ESPN agreement. Obviously, the "regardless of whether such member remains a member during the entirety of the term" seems to indicate that there must be at lease some rights that are necessary for the ACC to meet its obligations under the ESPN agreement, but since the ESPN agreement isn't public and Clemson's filing is heavily redacted, I would be cautious of anyone weighing in on the strength or weakness of that argument. I thought (and continue to think) that FSU's arguments are bad to laughably bad, and my gut says that Clemson's aren't strong either, but without the ESPN agreement, I don't think anyone can say that with any certainty.