The idea is to use the UAV to detect the missile launch and dispense flares that should divert the heat-seeking missile's attention.
This is apparently Honeywell's alternative to the more direct method of installing directed infrared countermeasure turrets on the airliners.
According to the patent application, here's how the idea works:
"This formation drone aircraft, which carries various missile detection and diversion equipment, is controlled by a wireless data link that is coupled directly into the airliner's flight control system.
When the formation drone determines that a missile is being viewed by a missile sensor head, the formation drone lays down a predetermined pattern of exploding flares to divert the missile away from the airliner, attempts to spoof the missile using laser countermeasures, or sacrifices itself to protect the airliner."