"NeuroRacer is not commercially available. We do not have any plans of release NeuroRacer to the public because it was developed as a research tool and not a consumer product."
http://gazzaleylab.ucsf.edu/neuroscience-projects/neuroracer...
http://gazzaleylab.ucsf.edu/neuroscience-projects/neuroracer...
http://gazzaleylab.ucsf.edu/neuroscience-research/donors/
They can't release it for free because Zynga wants first crack at making money off of it if it has promise as a commercial product.
Just a guess, but it sounds like less bullshit than their stated rationale.