The U.S. government is putting Americans on its no-fly list on a hunch
slate.com
slate.com
Besides, if the TSA/DHS went with anti-politically correct criteria, like say, Arabic style names, or attending a mosque or wearing a turban, even a total idiot will be able to find a Terrorist Sympathizer who's white, female, got a German-sounding name, and convince them to carry more than 4 oz of liquid through the nudatron in their hollowed-out shoes. Even dumber people will figure out that it's obvious you can circumvent the stupid theatre that anti-PC criteria would cause.
I bet the truth is more like the incentives that DHS has. It's better to keep anyone even faintly seeming or associated or accused of "terrorism" or similar things on a watch list, because then, when something bad happens, they've "done what they can".
Counterpoint: there's no reason there couldn't be an overlap between Deep State political correctness and the normal kind. After all, once one has made one's criteria for the no-fly list arbitrary, random and unjust, why not have them promote one's politics as well?
But that being said, you're on the money, it's the incentives. There's no incentive to make people's lives less inconvenient and more just, there's every incentive to not look bad in the media next time there's a terrorist attack.
Sorry, friend. I can't explain anything happening in the US government.