If this were the case it would just starve the bike out and it would stall and not start until it either sat long enough for the tank vacuum to leak down or the filler cap was opened. The more he describes it the more it sounds like an issue with the pump or plumbing.
11 year old fuel lines could be the issue. Sometimes the insides will deteriorate and you'll get a flapper on the inside that will intermittently impede flow. Or they get soft and don't bend as nicely and pinch. Maybe plumb in a pressure gauge and monitor it while you ride and try to force the failure, if it coincides with a fuel pressure drop, there's your huckleberry.