What really IS the problem here?
An image can be produced as nude, porn, educational, medical, scientific, commercial or just a picture.
An image can be seen as nude, porn, educational, etc, etc, etc.
In the end, it's a photograph of a human body engaged in normal human behavior.
Intent doesn't always equal reception and perception. The image that started this thread was not graphic. "Critical" body parts weren't shown although we all know they were there.
In the end, it's an image of a human body. Parts may be seen or implied. It's been known that some people have "fun" with Sears catalog of just an ordinary under-wears. (when sears still sent catalogs) In the end, majority of people alive have "fun" from time to time.
So... what's the REAL problem?