Random mobs don't try to sack a diplomatic location and also know of the "safe house" where the people are evacuated to, then go and sack that, killing the Ambassador. And that's just the beginning -- there are multiple additional reports of other attacks that clearly demonstrate extensive prior planning, command and control.

Rioting mobs have neither planning or command and control in place. They're mobs!

Has nothing to do with "free speech"

edited to add:
Al-Qaeda says ‘meticulously executed’ Benghazi attack ‘revenge’ for number two’s death
http://www.democraticunderground.com/1014232040