I never wrote that Bitcoins could be double-spent off-chain. Can't you read above what I wrote?

I said that the offchain coins would not be protected against a double-spend, meaning that the Bitcoin chain could still spend the coin again, which was also "spent" into the offchain.

The double-spend notion comes from the fact that the customer has gained double value from one original Bitcoin, the offchain coin and the Bitcoin coin.

If you still don't get this, please give up. It would mean you are hopelessly retarded. I tried to be nice to you for a few posts, but you just go on and on with your inability to grasp a simple concept.

Again readers, the above is JoelKatz's suggested attack, not the attack I described in my OP.