Well, inappropriate precision just highlights the question of what the uncertainty
is. If it's plus or minus $5, that's different than if it's plus or minus $0.50. That's assuming the analysis is otherwise valid.
Secondly, I don't see how "non gaap accounting" is relevant when the claim is that they are audited by an independent entity using standards which are not under their control.
Here is the link to the statement from the Post Office:
http://about.usps.com/news/statements/080117.htm
"By law our competitive package products, including those that we deliver for Amazon, must cover their costs. Our regulator, the Postal Regulatory Commission (PRC), looks carefully at this question every year and has determined that they do."