It’s not currently unfinished, at least from what i can tell. But you may be missing something *spoilers ahead*
If you go past their cave and the booth without interacting, then turn left past the bear. You will come to a beach.
If during the encounter you use rogue skills and abilities (sneak attack almost always guarantees the dialog) then the kid will tell you that you need to meet his boss and tells you how to have a positive interaction with him.
Skip the kids selling loot and go into the cave. He should be friendly now.
Alternately you can take the no honor among theives route, sneak in with just your rogue. Stealth AFTER he catches you but before he’s done counting… and he will stand there shouting while you pick his pocket and take over 250 gold, several potions and scrolls and other loot items.
