Probably, but it will still be insecure against a sufficiently resourceful attacker.

If you want the thing you're isolating to be useful to you at all, you will need to have some physical connection between the inside and the outside, i. e. a hole in your air gap.

If we extend this logic a bit, we also need optical and audio filters. Imagine maxing the fans and returning them back to normal speeds slow enough to be able to pick up the noise through a microphone. Or reading the RJ45 socket LED. So many ways to transfer data. It just comes down on how hard it is to exploit such a medium.