I generally like Michael Moore, but I think there are better documentaries about 9/11.
I think George Bush's politics were abhorrent and his war in Iraq was probably the worst US intervention in history in terms of consequences, so I'm far from a defender of Bush. But conflating a documentary about 9/11 with a documentary about Bush's politics makes a worse documentary than doing both separately IMHO.
Agreed. Bush was only in office eight months or so when it happened. His biggest 9/11 blunder was ignoring security advisors who were sounding vague alarms for several months.
This is a good place to start:
https://michaelmoore.com/movies/fahrenheit-911/ click on the facts tab