"He was just so angry we that we supported Kuwait"

I've no idea what Bin Laden's motivation was for bombing the twin towers, apart from the statement that he made describing his motivations. In which he goes into detail about the American-Israeli alliance (and in which he makes no mention of either Kuwait or Iraq):

    "Allah knows it did not cross our minds to attack the towers but after the situation became unbearable and we witnessed the injustice and tyranny of the American-Israeli alliance against our people in Palestine and Lebanon, I thought about it. And the events that affected me directly were that of 1982 and the events that followed – when America allowed the Israelis to invade Lebanon, helped by the U.S. Sixth Fleet. As I watched the destroyed towers in Lebanon, it occurred to me punish the unjust the same way (and) to destroy towers in America so it could taste some of what we are tasting and to stop killing our children and women."
– Osama bin Laden, 2004


It's fair enough to discuss what might have been additional motivations - but as someone said below - those were the motivations he publicly stated and as such I have no reason to assume his motivations were other than those which he publicly stated.