Might be emotions, might be just logic.
The siblings being emotionless would probably work on logic. Well in a logical sense, Judge and his alliances nearly got the entire bloodline ended (not killed since they had no fear) and the kingdom fallen. Now here he is allying again with another faulty plan. Logically, most machines should see Judge as the cause of the system/kingdom crashing at this point and eliminate it.
But they're still partly human, and the obedience hasn't really been explained well. So would the obedience to Judge overwrite self preservation? Or vice versa, who knows.