FEMA is supposed to coordinate to aid disaster preperation, response, and recovery. They have wide ranging powers to do so because there are a wide range of disasters out there.
Suppose you have 20,000+ stranded on a tiny island in the middle of a flood. Your air lifting in supplies but there are several news helicopters in the area slowing things down. You can't tell them to go pound sand directly but you can call the FAA and get the FAA to tell them to GTFO.
The smart manager delegates. Same in disaster response as in a dev shop.
I would rather the FAA, who do it day in and out and have response and contingency plans for every eventuality, be in control of the airspace than an agency with no regular practice.
Give unto agencies, that which is in the domain of those agencies. FEMA gives the directions for them to follow.
