Not really...? Quantum stuff is real, there are real quantum computers that have been demonstrated to really do quantum operations. They're not close to being usable to break crypto yet, but it certainly makes sense to get ahead of it.
> There wouldn't be so much effort going into bridging air gapped systems if even traditional encryption could be trusted...
These are completely different problems. Encryption just keeps information confidential. By itself, it offers no _security_ guarantees. Even the strongest encryption would be moot against a keylogger. Crypto can be (and is being) used to provide some security, like via signed code, secure processors, and the such, but security is a multi-tiered thing -- you want all the protection you can get, and like keeping data encrypted at rest, air-gapping is just yet another layer of protection.