Frankly, this seems pretty dumb and yet another waste of taxpayer money on some gee-whiz gizmo instead of actual investments in law enforcement. The very first comment on the Nature article indicates exactly what someone with real malintent would do when facing this system (other than the obvious, just walk away.) i.e. How would the system detect someone taking beta-blockers? (which suppress the heart rate and physical symptoms of nervousness - commonly taken by classical musicians before an audition and many others)

Whoops.