You have to go by the scenario presented, a SHTF situation where you have dispatched multiple armed looters already and the remaining have surrendered.
They are undoubtably armed, or were, so what do you do with them now?
I'm definately not going to smoke some random lowlife that breaks into my garage looking to swipe petty crap.
I would put him face down at gunpoint and call the police unless he presented a weapon with intent to use it.
He makes that choice and he dies.
These are two vastly different scenarios and that has to be taken into consideration.
The point WETSU is trying to make is that even if the shooting in your garage is justified, your posts here may come back to haunt you. So the guy in the garage comes at you with a crow bar and you drop him. If the prosecutor is on the fence as to whether or not he/she thinks it was justified, and some research turns up evidence that could make her think that you are a nut, waiting for the end of the world, it could go bad for you. You do not want them to find an internet site full of comments by you that say how you would kill survivors without remorse. In their mind, you may have just been painted to be a person that resorts to use of a gun to solve problems that could be solved differently. Those posts, taken out of context and delivered to a jury to support how you took the law into your own hands, could cost you your freedom.