That's the real question in the article. You'd think that even if the State Department was negligent in fortifying and guarding the consulate, the CIA would have a rapid response drill worked out with regional U.S. forces to protect their annex. I read that among other things the annex was a listening post. I imagine there is sophisticated electronics in these sites along with records and logs, access codes, and who knows what else.
I sense from the article that Benghazi, in the greater scheme of U.S. diplomatic missions, was a backwater post that was expendable. The only positive note in this debacle is the exposure of the Chinese fire drill Obama calls a foreign policy.
That is a fair impression from all of the revelations that have come out of this. Which is pretty darned strange given the prominence of Libya in 0coward's foreign policy. Amateur Hour all the way!