They don't. They are purely for helping you lock in a tax loss. They will give you roughly what we'll get for Morila ($1) and then charge you whatever their current fee is which looks like $150. I actually thought their fee back in the day was $500.
That's why he is better off doing it here. If he really wants to lock the loss people here would at least pay the transaction fees and make it a free ride.
FFX Price at posting:
20.0¢ Sentiment: None Disclosure: Held