Benghazi was on the 9-11-2012 anniversary. It was known to be a terrorist attack but the administration couldn’t let that get out with a looming re-election so they lied publicly (and shared the truth with family members like Chelsea Clinton immediately) so the lie was not for national security reasons with truth only shared to those with high security clearance.
Commie Brennan had to control the narrative. Attack the defenders who might spill the beans.
If they were indeed running guns to ISIS out of that embassy, then Christopher Stevens had it coming to him and got exactly what he deserved.