Stevens was a casualty before the security people got there.
If this was set up by Obama, then why did Stevens have a safe room to go to?
Stevens' death wasn't in the plans, of course. But it was an accidental event. He died of smoke inhalation...suffered in the "safe room".
And, as I recall, Sean Smith was concerned that the attackers knew the location of the "safe room" -- which is why he tried to lead the Ambassador out of it, but lost contact in the smoke.