Your extrapolating from your own course of thought and actions and assuming that everyone in the world makes similar enough decisions as you do that it's not worth considering alternate scenarios.
Not everyone has the luxury of deciding if some proof is good enough in a a consequence free thought experiment where they can also shape the constraints. IRL constraints and persuasion tactics shift the ability to verify, and someone with legal considerations can't afford to be wrong even once. It shifts the decision making process in such a way that the fact "cops have posed as reporters" plus an abundance of caution means nobody talks to reporters. Exactly the circumstances the AP is afraid of.
We are talking about people choosing to commit a federal crime out of the belief that it serves the greater good. If they aren't capable of being cautious, I first don't want them handling sensitive government information, and second, I don't want them making the decision to share it with the public.
Sure, but don't you see that your personal opinions don't apply directly to someone else leaking information, or more generally, chilling effects on things that aren't federal crimes?
Not everyone has the luxury of deciding if some proof is good enough in a a consequence free thought experiment where they can also shape the constraints. IRL constraints and persuasion tactics shift the ability to verify, and someone with legal considerations can't afford to be wrong even once. It shifts the decision making process in such a way that the fact "cops have posed as reporters" plus an abundance of caution means nobody talks to reporters. Exactly the circumstances the AP is afraid of.