I know they have a statutory obligation to comply with their ops manual.
In fairness to LB I think this was his answer but his vicarious knowledge of operating in the world of airline ops just does not allow for this:
You appear simply incapable of comprehending any scope for the exercise of any judgment or application of any wisdom contrary to a rule.
Operating outside the manuals is only available in an emergency and is explicitly stated in the airline manuals. Go outside the manual because you as an individual don't think it its sensible, wise, whatever will only get you shown the door. LB ask your ATO mate what would be the consequence of your scenario if it was a commercial operation. If you didn't declare a MAYDAY fuel even for two minutes into your reserve then CASA and the airline would be after your head before you left the flight deck.