I don't think it is an example of incompetence. It is rather evidence that clintoon didn't have the guts to face terrorism as a world war level issue so he ordered the trail to be dusted and Nichols/McVey to be the end of the issue. There are other examples of similar suspicious dusting to end the links ... plane shot down over Atlantic are near New York, plane that ... oh never mind, folks will just accuse me of taking off my tinfoil beenie.
I'm not sure it was even a question of guts. He had staffed agencies with cronies to the point that their efficacy was hampered, and had hordes of aides and staffers who never even got the appropriate clearances and background checks to be in the building.
He had, as a result (with the help of dame Hillary)thoroughly alienated the selfsame competent people he would need to prosecute any war on terror. I guess he didn't understand that the real professionals would have done their jobs if they had been allowed to.
Besides, terrorism, a war? What a real downer at the big party, maaaan...