To quote Celine Dion, "that's the way it is."
As to why, I think bigwhistle has a fairly
logical 
explaination - once A1 returns to the floor, his/her shot can count.
NCAA men's uses the same criteria (in NCAA men's, there is no airborne shooter rule) - once the shot is released, it will count (if it goes in) regardless of what A1 does (with the exception of goaltending/basketly interfering with his own shot).