And of course most deaths from terrorism in the US are from "mass shooters", who tend to be self-radicalised US nationals with fringe political beliefs.
Your source (correctly) says they were mostly from Saudi Arabia, which has a rather extensive history over several decades of terrorist attacks (both attacks in Saudi Arabia, and attackers outside of Saudi Arabia by Saudi nationals and/or with Saudi sponsors.) There is no sense in which Saudi Arabia is (or could be fairly described in 2001 as) "a place with almost no history of terror attacks."
UAE had no history.
That's a detail that doesn't matter. What matters is that we open the doors to men who have high risk of radicalization and ties to rich Saudis, bigot.