I think “he was right” is a pretty understandable if reductive reaction to learning about his articulated motivations in his own words for the first time after being told their whole lives that the attack was unprovoked and motivated only by his personal fury at the idea that America was “so free”. His explanation, while having plenty wrong with it, is more reflective of observable reality than the uniform narrative Americans are told by their government.

I’m not too terribly worried about American teenagers reading it and deciding that a life of committed Islamic fundamentalism is for them — I just don’t think the conditions are there to support that kind of thing being an attractive prospect — but I think learning to question imperial narratives, seek out primary sources, and consider the common humanity of people they’ve only known as caricatures are important steps in developing a historical materialist worldview.