I'm not sure why this needs to be solved in the bittorent protocol itself. It would be easy to build a solution on top of bittorrent.

Many clients already support downloading from RSS feeds for instance. It would be nice to have a decentralized way of handling that kind of periodic contents but if I understand TFA correctly the proposal embeds an URL for the updates, so it's centralized as well?

If that's the case I don't see the advantage over RSS. I'm a firm believer in the unix philosophy of having one tool do one thing and do it well.