There isn't any regulation that can fix people being jackasses. This isn't AirBNB's fault, and it isn't the OP's fault. It's the jackass who held the party fault. Could the OP have done things differently? Sure. It's likely the sublet wasn't entirely legal, and it's likely he could have renter's insurance. That being said, his insurance still probably shouldn't have to pay it. That is what AirBNB's cut should be covering. And I'm sure they will in fact cover it, as this is really bad publicity for them. The only reason for this post is to make that money get there faster.