I think of it this way, if you sat down and made up a game, would you make it the way Ponds are now? Or would you make it the way it 'should' be? I think almost everyone would design it in the most sensible way, which is to allow everyone to play until they fall, even if it means giving away a few extra days of eligibility to someone whose paid membership has expired.

It also seems that the goodwill gained by allowing players to finish their ponds, rather than marring the game for everyone still in it would be worth it.