Motives aside, I'm not sure how the OP can't lose money on this.

If he buys people's BFL "debt" now and BFL delivers, they're going to deliver to the people who ordered the units, not the OP.

If BFL gets to the point where they start refusing refunds, then it's unlikely they'll have any assets which can be recovered by unsecured creditors in a lawsuit.  I'm not even sure about how customers would go about legally assigning their interest in a "debt" which isn't yet due (it's not a debt until such time as a refund request isn't honoured).

What's to stop someone from selling their BFL debt to the OP now and getting a refund from BFL or taking delivery of their unit and making themselves and easy 10%?  BFL's under no obligation to honour any agreements made between their customers and third parties in respect of ASIC orders.

How is the OP even going to confirm that someone hasn't already cancelled their order and received a refund?  I seriously doubt BFL is going to share such information with the OP.