So I have a question that I have yet to see anyone ask or let alone answer. I'll try to word it neatly.
Scenario A: So we all know that in Lightning a channel partner can attempt to steal funds from their partner by transmitting an older state that's favorable to him. The only way to prevent theft is by having the other channel partner submit a more recent channel state and then the attacker is punished by having their funds forfeited. So in this scenario that attacker risks their current LN balance for w/e gain in older channel states he's submitting.
Scenario B: Lets say there's a merchant accepting Lightning payments and sells... hats for $20. A new LN user shows up and loads his balance to $20 on LN and uses it to purchase the 1 hat from the LN store, leaving his LN balance at $0 after the purchase. Should he now attempt to transmit an older favorable state where he still had the $20, then he risks literally nothing as even if he's struck by a justice transaction he'll forfeit nothing since his balance is zero. It seems like there's no reason NOT to attempt a theft attempt in this scenario since there's nothing to lose in terms of money on LN.
Am I not seeing something, or how are would be thieves punished in the case of a scenario where they risk nothing to regain their money back?