I asked him about this once.
He stated that if fuel was in the center tank and making the aircraft unbalanced, thus requiring it to be pumped to the wing tanks, the warning buzzer and light would have gone off within 100 feet of take off if not when the front landing gear left the runway.
If the warning buzzer and light did come one when they were supposed to have, why would the pilot wait several minutes and several thousand feet to start the pumps to remove the fuel.
As my father said, the damn buzzers are annoying and you would want to correct the problem ASAP, not wait.