Yeah qualified immnunity is part of the legal issues I'm not entire sure how it gets interpreted by courts.
I totally do understand they have an experience of the situation that doesn't get the benefit of a 3rd person perspective.
Regardless It was my understanding of legal procedure that courts do consider the actual facts of the case and not just the perspective of the people in it when determining if there's a crime and or punishment.
So I think there's a argument for manslaughter but ianal