It was clear who had the power in this situation. And when you’re face to face with someone with so much power, you behave in an unusual manner. You dare not take any action.
Sadly that's far from unusual. Meek compliance is how most people (myself included) tend to behave when confronted by federal or state agencies, regardless of how their privacy is being invaded.
If more people raised a stink, the number of US citizens subjected to such a thing would rapidly drop. People would not be dragged from airplanes or into questioning at the slightest hint of suspicion from highly questionable sources. You want to see what's in my storage unit? No problem, go get a warrant. As an aside - if the author was mistaken about its contents they just lied to a federal agent which itself is a crime, regardless of any original innocence).