But UBL got what he wanted right? The goal was the decline of the American Empire, and he managed it?

The goal was a Sunni Islamist caliphate stretching from Libya to Turkey. UBL wanted the decadent influence of the west to decline to the point where the teachings of Hassan Al Banna and Muhammad ibn Abd al-Wahhab could establish a durable nation where the correct practice of Islam could flourish.

The lesson Islamists took from the Soviet invasion of Afghanistan is that plucky freedom fighters can vanquish immoral foreign empires if they believe it hard enough. UBL in particular saw the lack of appetite the Soviets had for a protracted war while also lacking the perspective to regard the role of greater geopolitics - he saw the helicopters go down and he saw the Stingers but didn't see the half billion dollar a year budget or Pentagon-level planning and logistical support. He saw the dispirited Soviet troops but he didn't see Chernobyl or the black marketization of Peristroika.

Osama bin Laden took the milquetoast American responses to the Khobar Towers and USS Cole as a green light for a large scale domestic attack within US borders. it was the dumbest fucking move in terrorism since the assassination of Franz Ferdinand. It led to the perpetual occupation of Iraq, it led to twenty years of occupation in Afghanistan, it led to a changed dynamic with the Saudi royal family, it led to Houthi uprisings. It's fair to say that ISIS was UBL's goal but "NO NOT THAT WAY!!!!" in that ISIS was primarily decadent Europeans LARPing in the desert rather than enlightened Islamic scholars assembling an enlightened nation-state. ISIS also managed to rally the entire goddamn world against them by leaning on the piracy rather than the religious teachings. You wanna know what happened to ISIS between 2004 and 2011? It was UBL's missives-from-the-cave that kept 'em down. Everything UBL mumbled into a camcorder was anti-ISIS. Fast forward a few months past Abbotabad and we're breaking walls.

It's fair to say that the one single event that allowed the rise of MBS was the death of Osama bin Laden. Prior to UBL's death, American foreign policy required a nominally agnostic, nominally tame power structure within Saudi Arabia. After UBL's death American Foreign policy was able to adapt to a nominally fundamentalist, nominally disruptive power structure within Saudi Arabia. It was Osama bin Laden, after all, who objected to American bases in Saudi Arabia during the first Gulf War... and it was MBS who allowed direct El Al flights between Riyadh and Tel Aviv.

Osama bin Laden wanted the whole of South Asia to look like Talib Afghanistan. That's why al Qaeda capped Ahmad Shah Massoud two days before the twin towers. Fast forward twenty five years and the ruler of Saudi Arabia is WhatsApp buddies with Jared Kushner. Women can nominally drive. They're building ski resorts and billions have been spent importing European culture.

We all lost on September 11? But Osama bin Laden lost big. Things went exactly the opposite of how he thought they would. He was able staunch the bleeding while he was alive? But the minute he could no longer control the narrative, all hope of a Caliphate was fucking gone.

As far as "decline of the American Empire" I don't know if you've noticed but the only credible militaries in the world anymore are Ukraine and the Americans. Yeah Trump is a dumb fuck arranging Yemeni strikes over Signal but in Civ VI this is what you call "total cultural victory." That's an American jet, with an American soundtrack, aping an American cultural reference while saber-rattling against Americans. The co-opting is complete.