I am quite an open minded person about everything, including erotic pictures (porn is different from erotica). But webgizmos, what WE found a way to get out hands on was (1)quite difficult to get in the first place and (2)nothing like the trash you can see on the Net today involving human wastes, animals, children and violence where there is nothing erotic about.
Yes, I understand his concern, and would my own boys be a little older I would indeed be very concerned as well. I would totally freak out if I saw my son watching some of the picture not too hard to find "out there".
Of course, as a parent, you should talk to your kids, but some things we prefer not to mention. Heck I had no idea about "certain sexual activities" before I was in my early adulthood. Who wants to talk about sexual behaviors involving human wastes with their 10 year old?