This isn't quite so far fetched as it seems. Perhaps someone tried the dancing thing to see how a candidate handles himself in an awkward position under pressure in front of people. They found some limited value in it and wrote a blog post about it. Then other law firms started using it. It became a way for such firms to assess a candidates emotional strength under pressure. And now law schools are offering a 1 credit course in "interview dance". Seems to be the perfect analogy to what's going on here ;-)