Quoted from Thermionic:

While this specific lawsuit is probably ridiculous (for all the aforementioned reasons), it does serve as possible evidence that society has changed for the better with regard to the exploitation of children. Images like these now tend to be seen as exploitative rather than some cutesy artistic expression of irony or whatever, and are less acceptable to the wider culture than they were then.
The issue with this is quite simply that the baby had no ability to provide informed consent for the image, nor did he have the ability to revoke the consent provided by his parents. The fact that his parents may have signed-off is irrelevant, as they most likely had dollar signs in their eyes which clouded their judgement; they, of all people, should have possessed sufficient insight to realize that the baby may grow up and experience a severe negative reaction upon seeing the pics, rather than embracing it as "art" or whatever factors THEY projected to justify giving the OK.
Bottom line is, baby had absolutely no control over being exposed in this manner, and when this realization occurs to him as an adult the result can absolutely be severely distressing (perceived lack of control is a very big deal to people coping with traumatic events). It is irrelevant that he once embraced the image and may have even exploited it to get laid; the fact is, people grow and evolve throughout their lives and what was once acceptable may morph into something that is perceived as embarrassing or traumatic, and given that he was provided no choice in the matter it's understandable that he would seek a remedy.