When you do a pick up in store customer order, it is possible to reject order lines if they can't be fulfilled at the store. It would also be a useful configuration to be able to reject and cancel these order lines automatically if they won't be fulfilled at all. In practice this would be useful in a scenario where a customer's order can't be fulfilled since the store's stock ran out but they still want to pick up the remaining items on their order (and the company does not want to allow backorders).