If his trip's been changed because the itinerary he booked way back when has changed, compensation chances are zero. You have to expect when you book a trip months in advance that flight numbers, layover/conx times, departure times, etc. may change somewhat.

If his originally booked itinerary is still being operated, but he can't get on it again because it's now booked solid, then I'd say he's being inconvenienced and might have a shot at some Positive Space Upgrade coupons, though probably not in time for this flight. He should write a polite letter to Customer Care and gently suggest as much.