I don't see any dialog options for it though. I've checked absolutely everything everywhere. I've even checked if I can just sell it.
Hmm can you attach screenshots of what the questlog for the quest states, and also Rohan's talk menu?
Here you go. I also thought, that the option to talk about Seth would go away after talking about him once.
Hmm, I'll take a look at the code and patch it asap. Thank you for bringing it my attention, and for the screenshots!
