My view of self-defense is very broad.
I have always thought if someone comes to kill your family (as opposed to selecting a random soft target to steal goods), it’s only a matter of time until they come back.
As a juror, I would allow “Prospective defense of self and family” to forgive shooting in the back with blood running down your face, but wouldn’t go so far as going to an enemy’s house and killing them because of something they might do.
As it should be. These scumbags threatened his family. Who is to say they won't be back or do a drive-by? That is a reasonable fear. Kill them now. Let God sort out his own.