Good argument, although you missed a fundamental point that Al Quaeda follow the teachings of Sayid Qutub who was a vehement Islamist who made a damning report of the US in the 60s which became the foundation for the dogma of Al Quaeda and played a huge part in recruiting terrorists. It's neither one nor the other, but the seeds of Al Quaeda are in the teachings, not just the reaction to occupation.