You're assuming the staff wasn't calling all over to various stores and simply couldn't find one at any other store either. However, according to the news, the game's been sold out at all sorts of stores.
You're also assuming that an Edwards staff member wouldn't be conversant enough with his or her boss's policies to know that calling WalMart was verboten. That seems a rather unlikely, given that staff volunteers are normally volunteers because they support a candidate's positions on issues.
Given that, its more likely that a staffer would only call WalMart on orders from above.
There's also this to consider: Edwards has been attacking Wal-Mart in part upon the theory that it underpays its employees. It only stands to reason that Edwards, believing WalMart employees to be underpaid, would believe them to be unskilled and/or uneducated. Otherwise, why would they work at WalMart?
As such, it stands to reason that Edwards would assume that anyone who answered the phone in the toy department (or wherever) would be an underpaid, unskilled, uneducated, employee. Why wouldn't Edwards figure that a line employee at WalMart, eager to make a sale, wouldn't know of Edwards' anti-WalMart platform and wouldn't know enough to alert management to his apparent hyprocrisy?
If anything, its at least as feasible that Edwards would assume a WalMart employee wouldn't know who he was as it is for you to assume that an Edwards staffer wouldn't know his boss didn't want them shopping there.
