That occurred to me as well. Not necessarily the Iranian part, but if there are 20K manpads missing, some of them might have been with the attacking militia. A couple of observations:
1) If that was so, the whole operation of feeding arms and trying to buy back arms was fatally flawed
2) Sending the ambassador to Benghazi after pulling his security force a few weeks before was beyond incompetent
3) If we were too afraid to have overhead assets, why were the SEALS painting the mortar with their lasers? It implies the assets were there.
They could have taken them out with an armed drone.
Obama didn’t want to do it because he’d rather lose Americans than Muslims.