Flying on fires can be pretty full on. There are normally lots of other aircraft. Helicopters and Fixed wing assets laying down suppression. There are other machines controlling this suppression and maybe gathering intel and plotting the movement of the fire. There are also many people on the ground fighting the fire.
Here in Australia we set up temporary zones around the fire as the Fire authorities don't want anyone not involved in the effort in there as it is busy enough keeping a good lookout when you know what is there.
When a drone is spotted, the Air Attack supervisor will make the call to to send aircraft out of the area because the last thing they want is an aircraft damaged or brought down in the fire zone.
Fire suppression pilots don't want to be hit by anything if flying low level, operating near smoke over burning trees and bush. Even "A small Drone"