I just wouldn't use this method at all. If you are worried about your seed phrase being lost or burnt in a fire, then you should be twice as worried about your book being lost or burnt in a fire. It is trivial to make an additional copy of your seed phrase to store somewhere else (and indeed, having more than one back up should be seen as mandatory). How many people on the other hand have multiple identical copies of the same book, same edition, same print, etc.

There is literally no advantage to this set up when compared to using multi-sig or a passphrase, or just plain old encryption.