I suspect that this is to cover privacy issues. They don't want a repeat of what happened with the Netflix Prize. The Netflix Prize 2 was canceled because of

I suspect that this is to cover privacy issues. They don't want a repeat of what happened with the Netflix Prize. The Netflix Prize 2 was canceled because of the privacy issues involved with the data set (http://blog.netflix.com/2010/03/this-is-neil-hunt-chief-product-officer.html http://blog.netflix.com/2010/03/this-is-neil-hunt-chief-prod...). The FAQ states that participants will be randomly audited to ensure that they are satisfying data privacy standards.