Its also possible they would indeed stop 9/11 but that doesnt stop them from trying again later and maybe they blow up a sports stadium full of people instead.

Stopping one thing by no means means stopping future things.

Edit: just to be very clear here, stopping 9/11 short of taking out Bin Laden and the leadership would have just resulted in them planning something else amd trying again. They weren’t ever going to stop trying. We might have had intel about 9/11 but that doesnt mean we’d have Intel on the next thing.