Headline is deceptive. The threat of death is not required for the use of deadly force to be legal
4) The use of deadly force shall not be justifiable under this section unless the actor believes that such force is necessary to protect himself against death, serious bodily harm, kidnapping or sexual intercourse compelled by force or threat...
a person employing protective force may estimate the necessity thereof under the circumstances as he believes them to be when the force is used, without retreating, surrendering possession, doing any other act which he has no legal duty to do, or abstaining from any lawful action.
http://uniweb.legislature.ne.gov/laws/statutes.php?statute=s2814009000