Since no Pakistani was involved in 9/11 and the CIA-trained Al Qaeda was based in Afghanistan, ...
This is an often repeated myth that CIA trained and supplied weapons to Bin Laden, AlQaeda and other arab terrorists during Afghan war. The weapons supply, money and training from US and CIA were strictly thought Pakistan's ISI channels. Zia was very strict about it and controlled the weapons and money supply to groups that Pakistan favored like Hekmatyar. Bin Laden, Al Zawahiri and the rest of arab AlQaeda were fiercely anti-american from the very beginning. Their involvement in Afghan war was through other channels and limited. Saudi Arabia matched US spending to every dollar and saw Afghanistan and Pakistan as an opportunity to increase their wahabi and extremist influences to counter Iran. Egypt provided most of the ammunition and weapons as well as dumped most of its troublesome Egytian Muslim Brotherhood and Islamic Jihad members from jails to Afghanistan.
Imran's mentor Hamid Gul was second in command after General Akhtar to run the Afghan war and knows that in detail. One can assume that Imran knows it too but have chosen to misinform people.
Also, the 9/11 mastermind Khalid Shaikh is of Pakistani descent.