From my experience, if a book is loose in the inner well, it is loose leaving the factory, ie CGC, but it probably does not have SCS. The SCS develops later, from poor storage or multiple trips to the auction house. 'If' the OO notices the book is loose and returns it to CGC the problem is solved, however, we all know this isn't usually the case. Personally, I don't believe one should knowingly pass an SCS damaged slab onto another buyer, however, we all know this isn't usually the case. While I would not bother CGC with a small dollar book, I have sent them higher dollar books that had obvious SCS damage and they have addressed it.
They stand behind their product but only within reason.