I definitely interpret 'find a staffer in our understaffed store to unlock the case with this item' as 'this establishment prefers that you purchase this item from Amazon'.

Or at the very least, as "order the key which all these cases use off of Amazon, so you don't have to bother employees."

When I first went to the US 15 years ago I was upset by all the staff constantly trying to follow me around and sell me things (headphones, a camcorder, batteries) when I had not wanted or asked for their help. It's interesting how it has turned around to being no one there to help you.