Correct. I was suggesting simply putting doors on the racks and see if that helps with the sound, and possibly building them out. On my two racks, the difference with doors open and shut is pretty big. If it is pretty quiet in your theater now, with the racks wide open, I would think the doors would help quite a bit. If you don't like the look of the doors, or it isn't enough, I would then build them out some(with additional sealing/mass) and match your theater.
Certainly a false panel would do better, but I'm not certain the extra effort would be worth it in the long run--as putting doors on, would be pretty easy vs a false panel. Also, even though my equipment room is separate from the theater, I'm surprised at how often I need access to the rack.