I do not think we can ever judge justly from mere news reports. I do think it is always good to consider what is worth protecting with firearms.
Regarding civil liability, Idaho's statute defines Justifiable Homicide in a fairly standard "self-defence against a felony" way [see below]. "Defence of habitation" may be operative here, but the defence must also be against one who "endeavors, by violence or surprise, to commit a felony." I read that to mean that a felony must have been in progress AND the felony was through "violence or surprise."
Also, civil and criminal liability are two different animals. A lack of prosecution by the local DA (or an acquittal) is not a shield to civil liability. OJ faced charges in both criminal and civil trials. (Don't know whether he settled the civil case before going to trial or during the trial. Trials can be long affairs.)
18-4009. JUSTIFIABLE HOMICIDE BY ANY PERSON. Homicide is also justifiable
when committed by any person in either of the following cases:
1. When resisting any attempt to murder any person, or to commit a
felony, or to do some great bodily injury upon any person; or,
2. When committed in defense of habitation, property or person, against
one who manifestly intends or endeavors, by violence or surprise, to commit a
felony, or against one who manifestly intends and endeavors, in a violent,
riotous or tumultuous manner, to enter the habitation of another for the
purpose of offering violence to any person therein; or,
3. When committed in the lawful defense of such person, or of a wife or
husband, parent, child, master, mistress or servant of such person, when there is reasonable ground to apprehend a design to commit a felony or to do some great bodily injury, and imminent danger of such design being accomplished; but such person, or the person in whose behalf the defense was made, if he was the assailant or engaged in mortal combat, must really and in good faith have endeavored to decline any further struggle before the homicide was committed; or,
4. When necessarily committed in attempting, by lawful ways and means, to apprehend any person for any felony committed, or in lawfully suppressing any riot, or in lawfully keeping and preserving the peace.
[Full disclosure: I am licensed to practice law in Illinois, but not in Idaho. Since I copied the statute above from a non-official website, it may not be current law. Do not take this as legal advice.]