... it reveals that the executive branch is unwilling even to concede that a total ban on handguns would violate the Second Amendment. It would have been easy to write a brief that said: "The D.C. Circuit applied too strict a standard of scrutiny, so this Court should correct that error in its opinion. However, D.C.'s laws flunk even intermediate scrutiny, so the judgment below should still be affirmed." They deliberately did not do so. Gun rights proponents might not have been overjoyed by such a brief, but it wouldn't have been a big surprise, and certainly wouldn't have caused the uproar that the actual brief did.
