"But the risk posed by the issue — that the wing could become dislodged from the aircraft — was so serious that the Air Force decided to move forward with inspections for all planes that could potentially be impacted."
I would think that's a minimum standard, not a pretty high one. Having wings fall off is embarrassing, expensive, deadly, and nobody wants to testify before Congress as to why they let that happen.
One of the mechanics on an aircraft carrier I was on (briefly, I'm not military) said that if they find even one nut on the ground, they'll isolate and ground every single plane they think might be affected.