I haven't read the trial court ruling, but the appeals court ruling doesn't support OSI controlling the term. Rather, since both the plaintiff and the defendant agreed that AGPL + Common Cause was not a free or open source license, the court simply accepted that, and didn't have to weigh in on the matter themselves.

Edit: After reading the applicable sections of the trial court ruling, it is no different - the court simply accepted the plantiff and defendant's shared use of the term. It didn't reference OCI or FSF or any other authority.