Just a fire raging out of control 90 floors up is enough to imagine potential structural failure of the affected areas doncha think? We all can imagine what uncontrolled structural failure might do to a skyscraper and the danger this represents to it's neighboring buildings. In this particular case, we HAD an uncontrolled fire that we KNEW was being fed by jet fuel resulting in excessive temperatures. Knowing this alone, and we did, should have been cause for an immediate and full evacuation of all potentially dangerous areas, including the south tower.
Well, let's see. Apparently no one in authority on the scene DID imagine it; or IF they did, they might have thought that the people in Tower 2 might be at greater risk outdoors in the event of Tower 1 collapsing. If there had been just one plane in question (and remember that's all there was at the point in time we're discussing), the collapse of the first tower would not necessarily have meant the collapse of the second--thought it probably would have sustained heavy damage. I believe if only one plane had hit, only one tower would have collapsed. But we'd have to get an engineer in here to determine that.
We all can imagine what uncontrolled structural failure might do to a skyscraper and the danger this represents to it's neighboring buildings.
Again, I don't know that anyone there was imagining "uncontrolled structural failure". They were probably only anticipating a horrible fire, massive loss of life on the upper floors, and the probable eventual demolition of Tower 1, if they were thinking that far down the road.
These people have heard, since the buildings first went up, that they could withstand an impact from a 707 and STILL STAND. Why wouldn't they have believed that? And why wouldn't they also have believed that the fire would go out when there was nothing left of wood, paper, or sheet rock to burn on the upper floors, leaving the basic structure irreparably damaged but intact? That's what might have happened, if it had been a 707 heading to LaGuardia mostly empty.
Also, these guys were inside when it happened (the 22nd floor, according to the WSJ article linked above; try LOOKING UP to the 90th floor of the building next door from there). How were they to even know or assess the real danger of the situation in an area they couldn't see or access? They had no idea what type of plane had hit either tower unless they were watching television when the second plane showed up.
Easy to say what should have been done after the fact (except for the doors to the roof, which should have been unlocked, whether it would have done any good or not on 9/11--roof access is needed for other emergencies than an act of war). I still say it was a tricky call whether to evacuate Tower 2 in the minutes right after Tower 1 was struck. Events later proved it would have been the right thing to do, but I don't think anyone could reasonably have known for sure that it was the BEST thing to do at the time it was happening.