Air gaps are all about physical security
Most of this research(which I love for the lateral thinking involved) is exploiting the idea that the air gapped system isn't well isolated. This is why actual high security air gapped systems end to be behind security checkpoints, in access controled rooms, etc. The Gov had setup guides and rulebooks for physical security for several human generations, and handle much stealthier and higher tech attacks than these. If you didn't perform the physical hardening and isolation, you have an air-gap in name only.
While these attacks are an entertaining novelty, they aren't getting out of a properly configured SCIF. They do help highlight the multitude of ways generic PC and phone hardware make that process a nightmare. But using the pc speaker is old hat, and people have already done stuff over similar ranges using the ultrasonic whine of the transistors on the logic boards. People did TEMPEST attacks in the pre-cell phone era. They figured out a long time ago that if you wanted to keep a computer secure you should probably start by parking it in a sealed and windowless room, with access controls, behind a security checkpoint.
Biting the hand that feeds IT
