From the article it seems like Clinton opted against attacking for fear or possibly killing other innocent civilians or important officials. That sounds like a reasonable excuse to me, especially given that these opportunities were all years before 9/11. Besides, what would the ramifications have been if Clinton had issued such an attack? Furthermore, if the information had turned out to be wrong and the attack needlessly killed innocents, how many Republicans would have called for Clinton's head?
Now, if Clinton had the chance to apprehend Bin Laden and bring him to justice for the crimes he had already committed, as Bush is doing with Saddam Hussein(though ideally in a more peaceful manner), then it would be a different story. If there's evidence to suggest that was the case, I would certainly place a great deal of the blame for 9/11 on Clinton's shoulders.
There's a very, very fine line between an act of war and an act of terrorism.
