Allowing for the fuel burnt in flight out of that 10,000 gallons, take it that half the fuel was consumed in the initial fireball we all saw with our own eyes, then roughly 3000 gallons was left to do what you say happened? 3000 gallons perhaps 3500 gallons? Spread throughout a building that size by the time any reached the bottom floors would be zero?

Yes, because the buildings were literally completely empty and there was absolutely nothing else present to catch on fire other than the jet fuel.