If I've understood correctly, the point the GP was making was that 9/11 attacks were used as a cover for the foreign policy decisions rather than attempting to hold the perpetrators to account.

For example, what did Iraq have to do with 9/11? Nothing. What did Libya have to do with 9/11? Nothing. What did Yemen have to do with 9/11? Nothing. Did Guantanamo help keep the US safer? By many accounts, it mainly acted as fuel for the fire.

By declaring a 'war on terror' rather than targeting the specific groups involved in the 9/11 attacks, the US can now be engaged in perpetual war. How is that going to help make the US safer?

The actions only really make sense when you take into account the military-industrial complex and the desire for imperialism. 9/11 was just a convenient excuse used to push forward on those fronts.