I don't think you understand how a research organization works. This isn't three guys in a basement searching for child porn. It's a research institute at Stanford University. They'll have gotten funding to do the work by applying for federal grants, getting approval from multiple Institutional Review Boards who are charged with, among other things, making sure that the people involved in the research are appropriately taken care of. They'll be required to have counselors on board. However "legit" you think such an outfit might possibly be, multiply that by three.

This is their job. It is the same as if they worked for a law enforcement agency. When someone gets arrested for child porn, we don't also charge the police, prosecutors, and judges who might have to look at the material as part of prosecuting a case. I promise you Stanford isn't paying a team of professors and postdocs to just diddle themselves to kiddie porn all day.