I never buy gutted games from Gamestop either simply for a personal preference, but I can understand the argument. The game itself has never been played, despite the fact the packaging has been opened. Of course, to most picky people the packaging is what matters, but in Gamestop's legal terms the game itself is NEW in that it's never been played.
I kindof think of it as a similar circumstance with automobiles. The dealership is selling you what's listed as a NEW vehicle, but there are likely miles on it from being test driven and you really have no idea how many people have sat in the driver's seat.
Simply not playing the game is not the best criteria for considering a game new. They can get their greasy little finger prints all over it, drop the game and get it scratched, sneeze on it, spill coffee on it, but as long as it has never been inserted into a video game system, then it is still new?
Going by that criteria, that logic must apply.