Satoshium has something we call "Secret Extraction" it's not meant to be a backup in the same way as hardware wallets,
but rather it's an advanced feature to deal with various edge case scenarios, one of which could be aging or various types of damage.
Thomas here.
In short, backups are permitted but somewhat hidden / discouraged. Backup, or as we call it "secret extraction" is covered in section 2 of the Appendix.
There are two use cases for a backup. One, recovering a stuck redemption. The other is for value extraction, where the user is concerned about hardware failure and doesn't care about circulating the satoshium.
Of course, a backed up satoshium is non transferable.
In my experience, many users find backups anxiety provoking, and hide them so well that they forget where they were stashed. So, we allow backups for those that want them but do not see them as a primary usage mode.