http://science.howstuffworks.com/building-implosion.htm
If you mean that it was impossible because the extensive planning and prepping of the building would have been noticed.
An employee had told about a power down that happened several weeks before 9/11 and he had noticed men with big boxes and running wire everywhere. He said that the workers told him that they were running new phone cables.
After the power down was over, he heard a whole lot of construction going on and everyday he would have to clean large amounts of dust out of his work area.
Just another possibility, but he may have been just saying that too.