May I ask you, what do you think the primary role of the flight attendant is? Do you think they are purely there just to serve you coffee or tea?
No, the primary role of the FA is PAX flight safety.
The point here is that there is IMHO a higher risk of a rogue FA with terrorist intent getting inserted into a flight crew than there is of a pilot with a clinical mental issue alone on the flight deck or of a rogue pilot with the terrorist intent driving the plane.