Oh, I thought the Sam's Club was a Point of Sale advertising display run by Sam's Club. I now understand that you are talking about those kiosks like you see in the mall.
Your beef is with SprintKiosk, which is a Radio Shack company. Sprint does not own, manange or control the kiosks. Radio Shack is the company which owns the kiosks which sell Sprint phones. The rebate only applies to phones purchased from Sprint's own retail stores, not third-party resellers like Radio Shack. If you were mislead by the way the kiosk displayed itself, that fraud is on Radio Shack.
Sprint is trying to encourage people to go to stores/sites they own which are higher profit and also prompt accessory (huge profit) sales. They are not going to pay to have you go to what is essentially a hardware competitor. That's why the form specifies that the rebate only applies to phones purchased at a Sprint store.