Isn't it obvious? All information can be used against you. So if the targeted entity knows what you're training your agents with to appear like natives citizens, you can change that context or create traps.
In other words, they were classified because they were in use by the CIA not due to being somehow special.
It is the CIA. That's not the question. The question is what they considered "need to know" cause for these...
Because they were afraid of the effect a funny joke could have if it was unleashed on the general public. Reminds me of this: