The article specifically states that the intruder was charged with possession of a weapon for a dangerous purpose. Its likely the victims use of force prevented the weapon being used against the victim.

I get your example, and you should probably resist killing your ex. Any other rando appearing inside your house should be dealt with.

Now that's a disingenuous situation. Let's say she attacks you with a knife and in that lunge you grab her hand and make her stab herself. You still lose that.