It's a message board that discusses exercise and nutrition. He's a member who is trying a new diet.
You're saying "never" means he shouldn't be able to start threads about it?
The "never" part was a joke. I discuss my diet all the time. I discussed my increased plant consumption on here quite a bit. I guess that's what I get for not using emoticons.
The following part was not. If I had made a big deal about not knowing how to eat plants, then started making a big deal about eating them, I would understand when someone made fun of it. If I had made a big deal about not understanding generation nothingness' obsession with posting food pics, then started posting food pics and updating people on the changes in my diet, I would understand why someone would make fun of it.