It could very well be money laundering.
Send a legit bitcoin and they send you back 3 stolen bitcoins from one of the mt.gox hacks.
Send a legit bitcoin and they send you back 3 stolen bitcoins from one of the mt.gox hacks.
Given that they say their minimum 'deposit' is 1 BTC, even finding a handful of extremely gullible marks will be quite lucrative for them. That's all the motive necessary. It goes without saying that no one who sends BTC to this address is going to see anything back.
This is valid at any exchange rate, not just the current one.