The conventions do provide a degree of protection to organized civilian insurgency against an occupying power, on its own soil. But it makes certain demands that they be recognizeable when engaged in insurgent activities. The French Resistance in WW2, for example, tended to wear an armband when engaged in direct attacks, so that if captured they would be considered a "recognizeable member". A number of German officers served long terms in French prisons after the war because they ignored this caveat. These people, however, bear no identifying mark or uniform, and in the case we are discussing, are not on their own soil.
If you accept that they are in the employ of a legitimate government in some way, shape, or form, engaging in hostile actions in the territory of another government, not wearing a recognizeable uniform...the Conventions consider that epsionage and as such you have no rights under Geneva. You can be shot out of hand on capture as far as international law cares. United States law, however, typically demands a civil trial if it occurs outside a warzone and military detainment and trial if it does not.
However they are clearly not in the employ of a legitimate government in any way, shape, or form, and as such this becomes a matter for the civil courts.
