I also agree. If they had later flights, the World Trade Center would have been full of tourists too (they get 100,000 per day) as it was an incredibly beautiful day. Later would have given them options in other major cities across the counrty full of people, at least it was only the east coast that was in a "normal" work day.

Later flights probably would have had more passengers on board then the early ones did too, again, something they probably considered.