He had to know it was stolen. I work retail and if you scan on scan in a item that isn't up for sale the register wouldn't allow the purchase and if you somehow are able too your be fired on the spot.
http://kotaku.com/the-guy-who-got-the-xbox-one-early-isnt-banned-for-lif-1461593586
People have gotten consoles early from retailers before. The seller could have easily just told the people who bought them that Target or someone shipped them early by mistake.
Again though, time to move on.