the reason this happened in OK is not because they chose that location out of the blue - its because they already had an installed base of people there from the past which facilitated the logistics required to pull it off.
you may not care about why this location was chosen, but the people investigating it will surely be looking at its significance.
Do you remember Mousouri? Was here in Norman at the flight school. Nicholas Berg? In Norman taking classes. Two others in jail for helping Mousouri? Came here on student visas which expired long before 9-11.