This seems odd to me -- he is suing the government to ultimately win the right to save them money and give them better capabilities (if spacex isn't better, the government will just stick with united, and might even get a better rate as a result of,competitive pressure). Is it common to file civil suit against the ultimate beneficiary to force them to do something in their own self interest (to the detriment of a third party)?

The related example I can think of was "aerial refueling gate" with the leased aircraft, also involving Boeing.