Is it porn when nudism sites promote their lifestyle and offer pictures?

My guy is on a site that gives free daily pictures of this nudist lifestyle. He burned the pictures to a cd and there are women and some female teenagers on there. I'm sure it's for porn. He doesn't download men pictures. Couldn't he get into trouble for doing this. How would a site know what those pictures are really being used for. It's the pictures of teenagers that are troubling. The pictures aren't sexual and show no sexual activity with the women or teenagers. But the person downloading them could perceive them as sexual and they could be used for masturbation.