I work electronics in the Wal-mart here, and I am by no means the Dep Manager but I would thoroughly berate any of my fellow employee's that would do that shit. I have all the kinect stuff stacked and ready to go for the night of the 4th.
And yes, unless the sku rings up as " xbox 360 hardware" and not the specific sku, then yes it should ring up as "sale not available". The thing is, is that many times they will give it this generic sku that will always ring up, like they do with most of Nintendo's sunday releases. In stead of being "Professor Layton DS" its " Nintendo DS software" or something like that.
As for the manager selling it, I can see it. 2 months ago we had a customer purchase a brand new elite system, go home and crack open their broken old pro model and put the guts in the new elite shell and then return it. We are talking the inputs didn't line up, no HDMI port, and a wrong size/color and BROKEN hard drive. And the manager returned it even AFTER they called me up and I told them it wasn't the correct insides.