Eh, they still need to bug both the room where your computer is sitting, and intercept the actual encrypted files. (and get the person they’re spying on to decrypt a known file while their computer is under survillence). As a mechanism for circumventing legal requirements for a warrant, this isn’t really useful.
Mainly its just kind of neat. Its insane with all the different inter-mixed processes runing on a modern computer, people can manage to extract a 1024 bit number from your computer’s memory purely by observing the drops in voltage across components. Its doubly insane that they can extract those voltage drops by the noise emitted. And its triply insane they can do so with so inexact a set-up as just putting a smartphone next to the targeted computer.
Plus, I’m kind of amused to think of all the paranoids out there thinking the gov’t is spying on them will now sing commercial jingles loudly to themselves every-time they read their email.