Here's the thing. From the perspective of whatever entity, holding an interest in a successful 9/11:
** The individual attacks were meant to happen nearer in time to one another, than what took place (*see below). An attempt to cause the series of attacks was due to happen by momentum alone, as the offending individuals were aboard with the plan and presumably set to act (some, literally aboard airplanes). There could not be a do-over in the future, obviously, as the security loophole would become exploited upon the first attack. In other words: Failure at that point was not an option.
The shorter the time from beginning to end, the less apparent inaction would be. The longer the span of time from beginning to end, the more apparent that behavior, necessary to the goal, could and should be. (*no matter what particular beliefs are attached: a shorter attack time would increase the probability for success, as it is competing for the reaction time against itself - true, no matter which individuals were compliant with the plan, as nearly every other individual had/has legitimate intentions)
** Mr. Secretary and others would likely not have had prior knowledge of certainly the time and/or date, as it would be impossible - even for themselves - to control whether they would begin to act differently than otherwise, knowing a catastrophic event is immediately approaching.
Once the first plane hit the building, the event itself was in forward motion, and it became a matter of behaving in a way that did not offer resistance against what was happening. Nothing else was required. The fact that the event played out in the manner that it did, exaggerated the behavior to a point that the intent simply cannot be denied without answers that only an investigation could attempt to find.
** The ultimate goal is linked with an otherwise-unlawful access to information, which makes awareness, which decides power. We had reached a time in our existence where the potentially devilish lure of technology had become directly pitted against our rightful expectation for privacy, and 911 became a bloody, burned, tragic showdown within that effect.
Unacceptable concentration of power through ever-increasing, ever-faster means, is the most immediate and dangerous threat among so very many, and not necessarily the compromising of the typical person's email and phone calls - contrary to popular and ridiculous belief by the "Oh, but my email and calls are soooo BOR-ING...surveillance doesn't bother me!!" crowd.
Call the entire matter a message from God, if you will, because there is no denying it.