A/C privileged docs are not subject to simple FOIA requests. When I would do government work, we would use the header specifically to make it harder to get our research through FOIA.
Outside of the government, when the cyber crap hits the fan for a company and we have to communicate the gravity of the hack, everything gets routed through attorneys and gets marked as privileged.
With how BYU has been treated in the past around conference alignment, TV broadcast rights, and with the potential for financial due diligence for conference membership, it would not surprise me one bit that everything BYU-related to this Big 12 situation is marked as privileged specifically to keep BYU out of the tabloid-like soap opera that is expansion media coverage.