I was 13 years old when 9/11 and the aftermath occurred. Anybody who was there knows that the country was so shocked, so rallied to the President, that nothing Donald Trump said makes any sense. Bush was a new President faced with the biggest crisis since Pearl Harbor and he delivered. You saw it in his historic making approval ratings which held above 70% into late 2003. You saw it with the country rallying to his side.
Never...never did anyone come out on 9/12/2001 and say "It's Bush's fault". In fact, while neither President was really blamed, it became more of an off-color discussion about the foreign policy failures of Bill Clinton than George W. Bush. Remember the distasteful humor "Clinton was busy with Monica while OBL was planning 9/11". The attacks were planned for 5 1/2 years. Bush was only President seven months of them. The hijackers were in his country flight training before Election 2000.
So when Trump uses that 9/11 happened on Bush's watch thing, he's stepping into territory even liberals didn't go into.
^truth