Earlier quoted context omitted.
To be fair, look at it from totally the opposite direction to see their point of view. Your workers are under threat from poorly made postal bombs that could easily blow up during processing, killing your workers. Due to the vast volume of post you process, the threat is real and non-trivial. Do you do nothing? I think you obviously have to do something, whether you go as far as they did is what's up for debate.
> Do you do nothing? No, you coordinate with the CIA or FBI to investigate threats against the government.
If postal workers are at risk then it's within their purview (as it has been for over 200 years) to investigate and warn local offices in addition to other government offices.