Arguably, Stanley is no worse an overlord than most, actually. I'm not the one making that case, but I've seen it put forth before on the forums.
And from a purely practical standpoint, assuming the duty Parson feels is to GK and not Stanley, it would still be a good idea to keep the rocker around. He's harmless if properly managed, and it's not that hard to "manage" him, while also being useful as an Arkentool-attuned unit.
The whole point of this is lost if you keep it a secret.