The mention of absconding with his horns gives Noiz an idle curiosity over whether they have sensation in them. Would sawing them off hurt the troll? Or would it just be an annoyance to deal with as they grew back? Assuming they grew back. Who knows with alien species.

"An IOU. I suppose that's acceptable." For a moment he considers whether to ask about limitations and what might be off-limits, but ultimately shoves that aside. Nah. He's too tired to go negotiating the details. The troll sure is expressive, too, and overreactive, so it might prove more entertaining to blindside him with a request he'd balk at.