Basically, the government is immune from lawsuit unless it chooses to allow you to sue it. And this is the presupposition, so they don't need to justify it.
You've got only two defenses against this: (1) The right to vote; and (2) the right to keep and bear arms.
Yes, I'm aware of sovereign immunity, but the government has waived it for certain circumstances through the Federal Tort Claims Act. Since I'm not a lawyer, I'm nowhere near qualified to say whether or not this would be included in that exception, but it seems plausible to me that it might be. The act of the government seems to be non-intentional (I can't read the article due to a corp firewall, but it says "By Mistake" in the title) and it was committed by a person acting on behalf of the USG.
Basically, the government is immune from lawsuit unless it chooses to allow you to sue it. And this is the presupposition, so they don't need to justify it.
You've got only two defenses against this: (1) The right to vote; and (2) the right to keep and bear arms.