As soon as the child pornography argument falls flat on its face (assuming the prosecution is actually that boneheaded), the defense may argue that the magnitude of possible harm is very different considering how the body, mind, and memory of an infant hardly recognizable to their adult counterpart and that there is no sort of humiliating aspect to the album art that would cause the public to view the adult Elden in any negative way.
It's not as if Elden doesn't have some point to make. It's bad that he hasn't been compensated for being pictures on one of the most iconic albums ever made. But unless there's something revealed in trial that I don't know, it doesn't appear that the record company or the band did anything wrong. It all hinges on whether there was sexual child exploitation, and although some people on HN seem to believe that the image of the naked body of an infant is inherently sexual in nature (which is creepy to me, but what do I know), I highly doubt that a judge, jury, or regular people are going to buy that argument.