This doesn't sound like something I could get an exception for. Usually those are reserved for special events. I've never had a problem getting the override and used it this week simply by booking online 48 hours out. Using a travel agent rather than booking online would have complicated the issue. Of course, it's quite possible the GM of the Legacy SPG property is part of the Resistance to Marriott. Additionally, it's also possible that there is a disconnect between the Marriott reservation systems which provides this benefit and the Legacy reservations platform still in use at many of the Legacy SPG properties.
did Starwood have a similar benefit?