Having been to the "Big Brown Desk" at WHQ, with the FAA, the chief pilot, the entire cockpit crew and two ALPA representatives, trip-dropped, positive space with a paid hotel, if you roll up to the gate with 20 minutes of fuel onboard and a bored inspector looks into it, never discount the creativity of the Feds when it comes to personal interpretations of the FARs.
Yes it may technically be legal, but was it "prudent"? Personally, I'll take the most conservative interpretation.
Stories for over beer.