I'm not doubting you, but where did you hear that? Wow, what kind of data center installation is air-gapped in 2025, except for ... maybe military industrial complex (maunuf + military) and spy agencies?
Certain production studios (Commercial / Feature Entertainment) may have air-gapped datacenters. I'd expect anyone making an Apple commercial is doing that on air-gapped infrastructure.
Defense contractors, Pharma companies, basically anyone who has IP that they want to tightly control access to.
I don't have any details, but on their public website, they highlight LLNL (ELI5: US nuclear weapons research lab founded by Edward Teller) as a customer. I am not 100% certain they require airgapping, but it is totally conceivable that them or similar customers in that vein do. Oxide business probably selects for a biased sample of such customers (the customers that don't have esoteric requirements also have public cloud options AWS/GCP/Azure to choose from).
Everything that can be airgapped probably should be. Healthcare, education, public safety, social services, public administration. Anything that touches massive troves of sensitive data for an entire country or continent.
Non trivial amounts of industrial and civil infrastructure, sometimes the air gapping is also because there's no viable connectivity more so than security reasons (or you have to assume flaky network so the system is designed to operate as separated island 99% of time - for unlikely example Chick-Fil-A has such requirements for their k8s clusters running individual restaurants.
Sometimes it's also simpler to physically air gap a system than to deal with more complex security.
