The simpler solution used by airports I've been in is to post a security guard at the exit points whose sole and undoubtedly mind-numbingly boring job is to dissuade anyone from trying to re-enter the sterile area.
I have to wonder at the quality and positioning of their video cameras in Newark that they couldn't just lock down the terminal, print a screen shot, and walk through the terminal until someone recognized the guy's face.
Well yeah, there's that idea too. Although, I would think this would already be in place but obviously, I'm mistaken given what happened last night.