//Clarified : This is a hypothetical question that has arisen from a real world experience. If the premise is taken at face value, would one run afoul of the rules. (One entry in the thread clarified it for me, get a ruling from AA first). I've never pondered it before as I have never before seen U without C space until now)//

Is this considered inventory tampering ? As EXP You have purchased an international y. You apply SWU and wait list. Subsequently AA opens up saver business (u) but not SWU upgrade space (C). You take the U seat with your miles inviting a friend to go. The friend can't go and you refund the U space much closer to the travel date.