What I took away from this is determining whether or not someone is lying based on a series of questions while testing heart-rate, sweat, etc. etc. is fundamentally broken. The protagonist of the story chose to showcase it's flaws by showing it is easy to pass with proper training. He could have also shown how easy to fail due to any number of circumstances (like the stress of taking the test), but it is unlikely he would have garnered the attention he did.
It wasn't mentioned in this article, but it seemed like one major benefit of the training sessions is the fact that you know what you are getting into. I am generally an anxious person and that training and practice alone would alleviate a ton of my fears, regardless if I were lying or intended to lie. Knowing exactly what was going to happen when I walked into the room (ie: I'll be hooked up to this thing and that thing and asked a question like this) would be amazing for my anxiety. Would my anxiety surrounding the test affect the results the test gave? I know they do control questions but still...
I recently read an article that police are testing these big glasses thingies that are going to take your eyes and pupils and spit out what drugs you are on. The basis is pretty obvious: opiates typically restrict your pupils while amphetamines typically expand them. If we measure what happens to people under the influence of drugs and then compare then to users suspected of being on drugs, we could hypothetically determine what drug a random driver is on, right? The one very massive problem with this is the control sample. Using my eyes as a control to random girl 1000 miles away is bonkers and not a control. Using my eyes not on drugs as a control for my eyes on drugs would be better, but it is impossible to give people you pull over and suspect are on drugs. The other massive problem is there are any number of circumstances that would cause your pupils to constrict or expand and my eyes my not react the same way to those circumstances as yours, nor may my eyes react to drugs in the same way as yours.
Basically, just because we have the technology that allows us to do certain things, doesn't mean that every human body reacts in the same way to the same set of circumstances. It's dangerous to make assumptions or to develop technologies that supposedly give you a magic answer.