Kickstarter's TOS states that if the project owner can't provide a tier's reward to someone, they have to refund the money. And they must make a 'good faith effort' to do so on time.
I am not a lawyer, but I suspect the backer could take them to court for failing to follow through, since this is basically an agreement between the backer and the project owner, and the project owner didn't do their part. It'll be fun to see it tested in court.