Your use of "Civilians" tells us how easy it is to get hoodwinked by the usual media and UN rhetorical foolishness.
Use of "Civilians" in this matter provides nothing useful for applying an RoE that makes any sense. It appears to me that a profound lack of thought has gone into this operation, to include the political assertions of just what is to be achieved by the use of arms. Behind all of the rhetoric and noise, it appears that "support anyone shooting at the Daffy One" is the political aim.
If I oppose The Daffy one, and wear jeans and a t shirt, and boots, and carry about an AK-47 with the intent to "fight the man" how am I a Civilian? At that point, I am a combatant. I am thus a target, depending upon who you are.
Your post would suggest that I am "a civilian" for your purposes. (Or did I misunderstand you? It is a very muddy topic ... )