If these machines are denied outside internet access, but still connect to an internal network on which other machines have outside internet access, then that's a firewall, not an air gap.
You can certainly argue that, at a general level, air gaps don't work for the same reason teen abstinence doesn't work. They don't happen. But in specifics, particularly for infosec professionals, it should be your job to call out dishonesty. Not to not along sagely and say "air gaps don't always work". If your airgapped machine is breached, there better be a USB lying around, or a physical configuration change.
JFC, my Xbox is not airgapped.
(actually it currently is. But you get the point.)