It was not that long ago that nudity in boys was considered cute and a bit nostalgic. The summer camp that my son attended had a collection of old photo albums from the early days of the camp, and in some of them the boys were skinny dipping. Add to that the many excellent paintings of boys and men bathing from the 19th and early 20th centuries, and there is an argument to be made that many do NOT view this as sexualized.
Sure, if it's the same book, I knew an old queen that had a copy , but on the other hand I knew a married couple that were art photographers that had a copy too. I find it a bit too funky for my taste (not to mention too "posed"), but on the other hand this same married couple had a lovely and tasteful B&W photograph of their daughter, about four years old, climbing out of a bank of ferns with a seraphic smile on her face and (except for a crown of flowers) as naked as a jaybird.
If that (and all the other shots that were on the same roll of film but not selected) were introduced in evidence somewhere, would that be "proof" of anything?
I think the book they are talking about, which is out of print, crosses the line. Naked little boys bent over with their bottoms to the camera? And these aren't little bitty boys, they looked preteen to me in the pics someone posted.
I think, in this day and age, having any questionable pics of naked children is asking for trouble.
I don't think the book, by itself, proves anything. It's a combination of things makes me think MJ is guilty.