I didn’t claim anything :) - the words “pure guess” are a give away.

Pure guess here…

signal uses “magic” to encrypt messages at rest.

Part of this magic relates to the hardware.

Change the hardware and you won’t be able to decrypt the messages.

So try to move a message database to a new machine (either because you want to or because someone else has snaffled it) and you won’t be able to decrypt the database.