People forget Eddington didn’t just leave Starfleet. He abused his position as chief of Starfleet security on the DS9, stole Federation property, and shot Major Kira. He’s definitely a traitor. Had he just resigned his position, left Starfleet, and join the Maqui, they may have arrested him if he was caught, but not for treason.
Did Kira betrayed her uniform? That’s the reason.
People forget Eddington didn’t just leave Starfleet. He abused his position as chief of Starfleet security on the DS9, stole Federation property, and shot Major Kira. He’s definitely a traitor. Had he just resigned his position, left Starfleet, and join the Maqui, they may have arrested him if he was caught, but not for treason.