Maybe not, but large portions of pedophile collections are not prosecuteable as pornography. By collecting "erotica" rather than "porn" one can avoid prosecution.
Much has been made of the "less than 100 questionable images" factoid, when in fact, it is not necessarily the illegal images that condemn him, but the ones that normal people find innocuous and unremarkable. The overall nature and perspective of the entire collection will say much.