Perhaps but this would also remove any pretense of deniability from the manufacturer. If discovered it would just show that they went to great lengths (extra en

Perhaps but this would also remove any pretense of deniability from the manufacturer. If discovered it would just show that they went to great lengths (extra engineering effort to implement and hide) which could only be explained by the conscious decision to make it a back door and bypass it later in software. So the issue would no longer be one of ignorance (no button) but of premeditation (button with hidden bypass).