Let's start with one simple premise -- if you suspect that an object may be an explosive, you do NOT simply shoot it. You examine it and then remove it for a controlled detonation. So it's clear the border guards did not think that the computer was an explosive. Anyone on this forum who thinks that they were "just being careful" is an absolute cretin. If the guards even suspected that the laptop was dangerous, shooting it would have been idiotically dangerous. So assuming that the border guards were not absolute idiots, or insane, there's just one explanation left over: the guards wanted to bully Ms. Sussman, or teach her a lesson... using firearms. This sort of behavior happens all the time in third world hellholes. It has no place in a civilized country.
U.S. confirms ISIS computer expert killed in air strike (Reuters)
from the article: Police shoot U.S. student's laptop upon entry to Israel