That rather sounds like throwing in the towel instead of making your best efforts despite setbacks, but then again, Susan supposes one mustn't hold an angel to human standards. He really is such a useless angel though, isn't he? "That does sound rather frustrating," she says, kindly. It's not a test, as she has no interest in giving yet another pitiful excuse for a divine entity a chance to change her opinion of him. Rather, it's that - pitiful excuse for a divine entity or no - she thinks it would be rather foolish to anger him.