"Do you honestly think that the NSFW image that you linked to qualifies for "a reasonable person would consider the action depicted to be real"?"

Unfortunately the Register article is incorrect here. The test for whether a reasonable person thinks it's real or not only applies to the people being real, *not* the action. In the linked image, the people are clearly real. ("a reasonable person looking at the image would think that any such person or animal was real" - http://www.opsi.gov.uk/acts/acts2008/ukpga_20080004_en_9#pt5-pb1-l1g63 ).

The test for the action is merely that the image is "realistic". Images can clearly be realistic, even if we know or suspect it isn't real (e.g., realistic special effects in a film), and I think that the linked image would count.