I believe the answer may be that DC is "foreign territory" that Bidan is the head of.
The act of 1871, and all, makes the president the head of this "territory".
In essence, invasion from a foreign entity into the U. S. A.
Does it have anything to do with todays vote in the Senate?
For the same reason they use "Constitutionofthe United States vs
Consitituon ==for the United States.
It's a "look alike" shadow govt.
The same thing, only different.