If one substitutes one's original uniform for the enemy's (or another) to pretend to be other than what one is then the Geneva protocols don't apply—in essence, you're shot rather than be taken prisoner or war.
What these guys are doing is similar. When a State resorts to such action/deception then it's hard to see how the rule of law can apply. Essentially, anarchy has broken out.
From an outsider's perspective, it seems to me that the US is now so polarized that it's almost become ungovernable.
Heaven help the the rest of the free world let alone the poor unfortunate law-abiding US citizens who cannot help but be caught up in this damned mess.
The law of war doesn’t work the way you claim. At all. The Geneva convention specifically addresses non uniformed combatants and people wearing the wrong uniform, and does not permit them to be shot rather than taken prisoner.