They don't have to hold up in court to have a significant chilling effect on the job mobility of the employee who signed it.
I also to opt-out of Rapiscans and get pat-downs at the airport to stand up for my 'liberties'. After feeling violated after the recent 'enhanced' one where some dude rubbed every part of my bait and tackle for 2-3 min I decided to give up that fight to. No money though.
Modern America, eh?