Kiwior seems like a good sport but you can't have defenders without atheticism and aggression in a dynamic team. He'd do well for a side where he just has to defend his area, but his limitations are what they are, and I don't think many would argue that he has developed any particular skills at Arsenal. Recuperating the money is fair and everything else is a bonus. Like Meatwad says, we don't buy guys like him to make a profit, we buy them because there's a possibility they might become starters.
We spend so much time being outraged because somewhere there's a Chelsea player who was sold for a better fee, but keep Kiwior another season and those extra millions plus some will be gone in wages anyway for a player we no longer need. Just thank him for his service and give him the boot out the door. Being proactive with outgoing transfers is as important as being proactive with incoming players.