The later part of your analysis tend to support the theory that they were: 1) Arabs. Because it is alleged the Arabs occupy these apartments. After all the stereotyping still prevails.
2) The fact that they had shot down one of the aircraft is? Considering all things done/achieved on mission 911 the White House means too much to our history, I think the planners taught that they went to far or sympathy for the president is just what the Doctor had ordered……SHOOT! It down in the aftermath our theory will suffice.
But was this part play acting?
As the security services learnt of the first plane diving into the WTO the Commander in Chief took to the sky with the largest most sophisticated and most expensive entourage setting a new world record any coward could have achieved but they had to head underground as the Angels knocked on air force 1. reminding the President that he could not stay up in the skies forever and the nation fire fighters were braving the catastrophe with less means at the time the people needed him.
Indeed the best example of any worrier is he who leads by example not in abstain[CIA].