Cell phone blocking versus jamming
When ever I read stories like this, I have to wonder if anyone with actual technical knowledge of the systems involved was ever consulted.
This is a cellular telephone technology we're talking about, not cold-war era broadcast technology. Calls are able to find their destination cell phone by way of the closest cell tower/site in the network. If you were to put a micro-tower in the theatre, all cell phones would automatically connect to it as the closest point of access to the network. Control that access point and you control the cell phones.
Those cell phones connected to in-theatre sites wouldn't ring unless permission was granted on a per-number basis for doctors and other emergency personel. Obviously, it needs to be dead-easy to enter numbers into the system, either manually or automatically. The system would also be able to automagically handle outgoing dialing of 911 and other emergency numbers, regardless of whether a person's device is registered.
Those cell-phones connected to in-lobby sites would ring and act normally. You would probably need in-lobby sites so the in-theatre sites don't over-extend their reach.
Problem solved, and the only involvement of the FCC would probably be in the qualification of the equipment within existing regulations. No need to grant special permission for entertainment-purpose jamming gear.