General question about this and other types of online activism that dance a fine line between "legal research" and "convenient access to something that is illeg

General question about this and other types of online activism that dance a fine line between "legal research" and "convenient access to something that is illegal" -- are all of these investigations sanctioned and signed off by a LEO? My limited understanding of the legal codes in the United States suggests that it is very difficult, without formal approval, to research a subject area like adolescent erotica without being exposed to the same images that would constitute possession. Is that what is happening here? In the article I see the mention of LEO working with the Foundation, but what isn't clear was if that is the only way they get involved, or if they get involved and then LEOs seek them out for assistance. The last thing that I'd want to see happen is for a set of good intentioned individual to get wrapped up in a covert LEO activity and then lumped into the same pool as the people they are trying to bring to justice.