This has got to be the dumbest thing I've ever heard of. They have no way of knowing if she did it. They gave her her a flip phone and at the end of a year they're going to have her take a polygraph test. That's the setup. Wow.
That being said I think you should reframe your thinking on this- they got over 100,000 applicants and a ton of press. My guess is they were always planning on paying out the $100,000 and the polygraph test is just another way they can throw some marketing around. The Vitaminwater brand has over a billion dollars in revenue for CocaCola each year- rising up from $350 million a year before coke's marketing team got ahold of them. Their marketing department knows what they're doing, and this $100k is a drop in the bucket for the press it's gotten.