The only “loophole” that might justify DC’s ban from a legal standpoint is the “no STATE shall” portion...since DC isn’t a state.
However I don’t think that’s enough to uphold the ban. Then again I’m not a lawyer. I’d love to hear Fred Thompson’s take on the matter.
The only loophole that may work is the claim that RKBA is ONLY for militia service: that if one is called up for militia service, there is certainly an extra minute available to unlock/assemble/load otherwise non-functional firearms; also that handguns might be deemed largely useless for militia use. DC is trying to eliminate home defense, period; claiming a loophole for militia-only use is their only hope.