Hey, staying awake on the exit lane is just about the toughest part of my job!

Edited to add: I think the actions taken by the TSA in this case reflected not only the threat posed by the passenger in question (obviously low) but also concern over who ELSE might have gained access while the exit lane monitor was absent or asleep!

We had a breach at my airport a few months ago -- a trainee was left alone on the exit lane. When no one came to relieve her at the end of her shift, she simply got up and left! Oops. Needless to say, the mentor who was supposed to be shadowing her at all times got a serious butt-chewing, as did she. Don't think they dumped the checkpoint over it, though ...