What makes you think the police officer feared for his life?
Maybe he felt threatened, maybe not; however, interpretation of edged weapon defense training may be an issue.
Article: “However widespread that contaminated interpretation may be, it is NOT accurate. A suspect with a knife within 21 feet of an officer is POTENTIALLY a deadly threat. He does warrant getting your gun out and ready. But he cannot be considered an actual threat justifying deadly force until he takes the first overt action in furtherance of intention—like starting to rush or lunge toward the officer with intent to do harm. Even then there may be factors besides distance that influence a force decision.”
The deceased had a weapon and apparently did not heed police officer commands to stop.