I don't doubt the aircrew believed this to be true. At the same time it suggests the phrase was probably Allied propaganda that made it's way into the conversation in whichever theater of the war the Beau was flying.
I tend to agree. An effective propagandist would likely coin the nickname, but give credit to the enemy.
What better way to boost morale than to let them know that the enemy is so scared/impressed with our weapons that they give them grandiose, fearful, impressive nicknames?
