Oh look, another thread for the transphobes to display their hateful bigotry!
Seriously, if an officers needs lethal force to stop someone with a knife, something is deeply wrong with their training. There are other ways of dealing with the situation than killing a person. Police officers are supposed to react with proportional force, not overwhelming lethal intent. Any civilian defending against a knife by using a gun and killing the other would get sued into the ground and end up with doing time. The fact that it's a police officer, who are supposed to be trained to deal with this kind of situation, makes it even worse.
But hey, don't let me get in the way of you bloodthirsty people celebrating a person's death.