Here's how the scam went down along with his admission of what he was doing...
https://bitcointalk.org/index.php?topic=206948I am giving away at least 1 BTC per address on Ripple.
https://bitcointalk.org/index.php?topic=206948.msg2166536#msg2166536B) I won't defraud/scam you out of any money. Yes, you can convert the BTC I send you to real BTCs. For continued discussion, send me a PM, responses will be deleted from this point.
I PM'd him to ask him how he would deal with redeeming IOUs so that anyone could convert his IOUs into BTC. He wrote...

So in summary he misled people, while counting on their ignorance of how Ripple works, into letting him put them in harm's way so he and his confederates could steal their legitimate IOU's from reputable gateways.