Overly Paranoid.
While I applaud the fact that these guys went ahead and sued the US Government ahead of doing something that is albeit gray, I have to wonder if they were being a bit paranoid.
The researchers can still be sued in civil court over any implied breach. This judgement doesn't stop that, however it does stop the government from going after them. IMHO the government wouldn't have gone after them in the first place. They aren't hacking/breaking the site. They are using it within its constraints, albeit creating 'fake accounts' as a way to verify the algos. So the website's code functions as it was intended. No criminal act.