Interesting, since I have seen some LL games played with 8. Our local LL allows 8. I don't know if that is a local rule or if they just ignore the real rule.
Officially, a LL game must start and finish with nine. But local rules (especially when it may be tough getting enough players to start the game) may vary. I don't know too many people who are real sticklers for LL rules when it comes to getting rec kids to play a game under whatever circumstances are presented.