Oh damn, I didn't even consider that they wouldn't refund if BFL had no more money in their PayPal account. It shouldn't work that way though because I run an online business with PayPal and PayPal simply deducts it from your backup payment source. Losing a claim is losing a claim and payment is required. At least that's what I thought. I would be pretty surprised if they thought my claim was legitimate but didn't make BFL pay just because "there wasn't enough funds in the account".
Well, I'm pretty sure something like that must have happened somewere in past, even if not in the bitcoin world.
So, it should be known what happens.
I'd say it's quite likely that if they want their money, they'll take it from your bank obviously, and if your bank account is zeroed I guess they might bring you to court.
However, as I said, I think it really is known what happens in this case, it's only matter of finding someone who
does know it.