but I remembered that most of the physical access hacks would not be possible if the disk is encrypted.. which then makes this kind of hack enormously attractive.
The antenna idea can be extended to be a piece of hardware with the interference device built-in (piezo or whatever) which communicates with the external world with any wireless medium and then the attacker can trigger the interference remotely. This, plus a website controlled by the hacker which the victim is scammed to visit can be enough to make it viable.
Only if you have not booted into your system through using a keyfile or a passphrase to decrypt the data, i.e. if your PC is shut down. I have full disk encryption, and when I boot into my system, it uses the keyfile with which it would perform the decryption, and boom, I have my PC ready to be accessed physically.
Also don't see how the article's exploit would be useful pre-decryption.