For reference, part of the motivation of the new announcement system was to be able to do stuff like this. It will check our S3 folder on startup and every 60 minutes, and will only download/save files that are signed with our offline key. This includes being able to periodically update the bootstrap file between Armory releases. If someone compromises our AWS/S3 account, the best they can do is DoS these announcements, unless they also get our offline Bitcoin private key.
For that reason, you can always stay up to date on the latest torrent simply by watching the bootstrap.file in the atisignedannounce folder.