Might be going crazy, but wasn't there a way to actually speak to the Lost Naga at some point? It's been a while since I've played.
Tbh, I think there's something more with the naga, but can't find what (other than eating him, making him fuck your slit and loosing to him). There's another option, where you can fuck his slit, but I can't get it. I don't know if it could be tied to being able to talk to the naga after, but well. Otherwise, I don't know, maybe it have been removed, or you're just crazy x)