Running in:
Whilst it is correct that a requirement is present in FAR/JAR 29.927(c)(1), it could be interpreted that is it conditional upon the assessment that some (loss of gearbox lubrication) failure modes are
extremely remote; this might trigger request for an Equivalent Level of Safety (ELOS) assessment - which would propose mitigation only of those elements which fall short of the
extremely remote categorisation.
(1) Category A. Unless such failures are extremely remote, it must be shown by test that any failure which results in loss of lubricant in any normal use lubrication system will not prevent continued safe operation, although not necessarily without damage, at a torque and rotational speed prescribed by the applicant for continued flight, for at least 30 minutes after perception by the flight crew of the lubrication system failure or loss of lubricant.
Which led to my questioning of your simplistic assumption. (It could be suggested that it is difficult/impossible to satisfy the requirement for a 30 minute run-dry gearbox for helicopters above a certain size - hence the use of alternative emergency lubrication systems, or failure assessment.)
No regulation can foresee all future uses/interpretations; that's why we see the introduction of hedging statements - to avoid the law of unintended consequences.