I think you're missing the point of the article. I've noticed that a couple of readers who have commented are coming from "all or nothing" perspectives.
If you want to pick apart this system for every scenario, that's your business. The point of this piece is that you can use 802.11b and backup for "in between" archiving. This does not replace you're existing secure, robust backup system.
Sure, I wouldn't use this method to backup secret plans to take over the world. But to save two hours worth of regular work that I don't want to lose ... backup and 802.11b is sweet and very useful.