No. It would work most of the time though. If they said online wallets are ok, then every so often such a tx will occur naturally and the person will lose their BTC. The change can sometimes be 0.00543210 but it would be pretty rare.
And even without that, it isn't fail-safe. From a normal client if you accidentally don't set the other bet to exactly 0.00543210 or forget to put it in the return payment will just come back to you. That is fail-safe, it fails in a relatively safe way if something goes wrong. With an online wallet, if you mess it up in any way the return payment goes somewhere not good.
For people who don't want to use a regular client, blockchain.info wallets work great with satoshidice.