I think it is very difficult to determine the intentions and motivations of the "authorities" involved in these situations. It occurs to me that whoever got on the horn and told everyone to return after the first plane hit probably remained inside the WTC and very likely may have perished. Remember that the "authorities" pull their pants on one leg at a time, just like the rest of us; They are basically trying to perform their duties properly, and like all humans, sometimes they get it right and sometimes they make decisions that, in hindsight, are "less than optimum."