There is no contradiction. All had approved visas. The pilots were here since 2000. Some visas had expired. It was an intelligence and bureaucratic failure. And it will happen again, Trump or no Trump.
I stand corrected.
A half-truth is not the same as the whole truth.
Yes they had approved visas, but "National Review’s Joel Mowbray acquired the visa applications of 15 of the 19 hijackers and exposed how every single one of their applications should have been flatly rejected" - based solely on the answers and/or lack of answers to the questions on their applications. See Link1, Link2, Link3.
For a President who made homeland security his priority in January 2001, it would have taken only simple Presidential directives to restore such immigration policies to the pre-Clinton standards of "enforce the law." GWB was too busy with his priorities of Open-Border (with Vicente Fox) and "No Child Left Behind"(with Ted Kennedy) to be that President.
As Trump stated, Bush did not cause 9/11 but he did nothing in his 9 months in office before 9/11 to make America safer than under Clinton - and Jeb should have been called out on his claim.