Well, top secret information isn't permitted on internet-connected desktop computers either.
But the thing about desktop computers is that they're not connecting to cell towers all the time. So if WiFi is disabled too as a precaution, and they're only connected to private secure networks via Ethernet and not the internet, you can consider them secure in terms of protecting classified secrets.
I don’t think many people understand how the TS or Secret networks of military bases are connected.
It wasn’t long ago that we were subject to stringent military standards for hosting these networks on site but once they came through, there was never any re-certification.
