I completely agree with you, Rally and Ver--that the base claims are ridiculous and not worth concern. I don't personally care if he wants to accuse me of having a waifu or an attraction to cartoons or whatever--the problem is that he has attached information that literally links a photo I had posted to the IRL pics thread as my resume portrait to claims that I am a child predator. My employment, academics, sport activities and even public forms will directly link to those ridiculous claims about me. That's literally slander--which is a crime. I specifically stated that there was zero chance of any sort of legal action, because that would be absurd. The problem is that Beachbum has repeatedly made extemely harmful claims that could easily affect my life. I laughed about it and ignored it hoping that he would stop--because how long would he really keep it up? After several months, I don't really see signs of stopping.
How would it make you feel if someone repeatedly compared you to genuine rapists and monsters alongside images and information currently held by your school and employer? I don't think you'd find it quite so funny when people you really know and work with could easily stumble upon those sorts of claims during a background check.