Responses

they'd just be murdered for attempting treason against the tyrant since he's still the official emperor or whatever. He'd immediately know something was "different" in the palace because he's either good at reading people or he just has heaps of experience in figuring out those sorts of things & then he'd go on a rampage the minute he found out they tried to form a union since it could be the first sign or minor attempt of a revolt (from his POV anyway)
The servants should unionize, working under those two sounds stressful