Why couldn't they just use a brain wallet on an offline device with no internal storage.
Keep a hand written copy of the generated passphrase laminated in some plastic in some fake plaster rock under a tree in a wood or something.
Take it easy Andy Dufrense
The idea is this would survive a search and potential jail term.
maybe he backed up to icloud by accident
This. It's harder than you may think to leave zero cloud trail of your activity and storage.
I bet he just got opted into iCloud Drive documents and desktop folders.