I disagree. First we had forces in and around Saudi Arabia, second, we trained the Saudi military, and could have counted on them to back us against their rulers, and third, the rest of the world was in chock as to the extent of the World Trade Center tragedy, and the Saudi citizens Jihadists, to the extent that most European intelligentsia say they would have backed us.
The fact that we did not invade Saudi Arabia instead of Iraq remains because of well connected people in Washington still are on the Saudi payroll, and provide lobbying, and public relation for them. Saddam was a wounded dog, and easy to kick around at will.
The real source of Islamic terrorism is fanatic Islam as it is being spewed by Saudi Arabia, and Iran.
Actually, even Moslem nations were very much aware that the Saudis were behind that attack on America. In addition, the Saudi royal family are not admired anywhere, so taking them on would have been simpler than the so called experts may have thought.