The DC carry permit is hard to get, but from what I've read, another reason it has so few applicants is that it is almost useless for actual carry. The list of GFZs is onerous. Here's one I find especially ironic, Carry is prohibited:
When a dignitary or high-ranking official of the United States or a state, local, or foreign government is moving under the protection of the MPD, the U.S Secret Service, the U.S Capitol Police, or other law enforcement agency that does not include a distance greater than 1,000 feet from the moving dignitary. (provided notice has been given by signs or an officer’s order)
OK, that probably happens many times every day in DC. It says notice must be given, but it doesn't define what that notice has to entail. And what if you are carrying, minding your own business, and a motorcade comes around the corner? Are you supposed to run 1,000 feet away? And would that even be a good idea? So the protective detail sees someone running away up ahead? What could go wrong with that? It would be hard to avoid that restriction just driving down a major road or highway.
That combined with the other 17 GFZ restrictions makes it really problematic. AND...There are additional federal restrictions all over DC.
Back to the incident in the OP, I am reminded of that Air Marshal who left his Sig on the toilet paper dispenser in a bathroom stall in an airport. It was found by a young boy, who fortunately told his Dad, whole called airport police. But there was never any statement from DHS that the agent had been disciplined. He probably got hollered at, but they have a hard time keeping people, so I will bet he didn't get fired.