"Organizations preserve routines that once prevented failure.
The hard part of an architecture review where two constraints collide is not the technical detail; it is choosing what happens next while the picture is incomplete.
Under pressure, people default to the simplest story. If you do not define the boundary, the simplest story will define it for you. Define the decision rights before the crisis, or the crisis will define them for you. If the exception path is informal, it becomes politics; write the signal that makes an exception legitimate and who can approve it.
Write the hidden assumption as a sentence, then choose the signal that would break it. That is how you stay decisive without pretending to be certain. Make the decision legible to the next person who inherits it.