The War of 3039 had not started yet. The FedCom wanted an excuse to start the war. It instigated several rebellions on former FS worlds, and when the DC cracked down hard on them, the FC claimed they were moving in to save the poor people of those worlds.
So the support couldn't be seen to be wearing FC uniforms. They were claiming to be local militia and/or mercenaries hired by the local government.