But then that raises the question: Why is their guilt over possibly having contributed to a situation more important than the lives of people who could be killed by serial-killer-training-demon, but their desire to not torture and murder innocent people in general not so? It seems to come down to that they had empathy for Nora, and a connection to her. But her won is undoubtedly not the only possession victim with family who are desperate and terrified and will do anything to get them back. But since Sam and Dean don't have to look that family in the eye, they don't count.