Actually, a government agency like the US Postal Service calling themselves a brand and wasting money sponsoring athletes (Lance's Tour de France team) is a misuse of taxpayer money. They should be 100% focused on the reliability of their primary product, which is delivering the mail on time. "No matter rain, nor sleet, nor snow... the USPS delivers" used be their mantra. Have you sent a package with them in the past 2 or 3 years and tracked it? The USPS is now a perfect example of government inefficiency.
So, should USPS be upset that Nike modeled a shoe after their "brand" of s—? I would think they should see it more of a compliment. The bigger question is why Nike would want to associated itself with USPS in any way given their poor performance and reputation?
Maybe it's Nike reflecting it's own decline?
Or maybe everyone has lost their sense of humor?