The seller's trying to create value by pushing the rarity of the defect. The fact that it's been bid this high and the reserve hasn't been met is a good sign that this seller had huge dollar signs in his eyes, once he got over the fact that his deck was defective.
It's kind of odd to me, though. Aren't the decks hand-packed into bricks and boxes? Wouldn't this have been caught by USPC? It's either the tuck sheet shifted when it was folded into a box (less likely, since I think it would not really form into a box, just an open mess) or that the tuck sheet was a little off-center when being cut (more likely). That would mean that this deck may be "rare" but not exactly one-of-a-kind, either - all the other boxes on that sheet would have the same defect. I can see a card defect getting missed, since packing the cards into boxes at USPC is completely automated, but once they've been made, I'd think someone in QC would have spotted something. Unless they are also automatically packed into bricks as well, of course. And even with an automated process, aren't the new facilities equipped with laser sensors to detect off-center prints and cuts?
Someone with a more intimate knowledge than me would be able to answer these questions better than I could.