> He stole data but did not place it in the public domain. Instead, he handed it over to a group of journalists who were given the function of filtering the data before publication

I understand that, but strictly speaking it's not relevant. He stole the data, and is therefore responsible for whatever eventually gets disseminated - good and ill alike. As far as ownership goes, it doesn't really matter if it was eventually published via the Guardian, Wikileaks or his nextdoor neighbor.