China will definitely block xmpp on any port. I know this because I have tested this very specifically from my own server. It lasted about a day and a dozen messages before it was blocked, and the box got absolutely slammed with vulnerability scans.
It also just gets blocked by autocratic firewalls. Deltachat is clutch because it can theoretically run on top of any email host so it’s way more difficult to block.
The protections for classified information are not just about information security. They are about physical and operational security as well. That’s why s SCIF has a “two locks” policy, and requires things like 4" steel doors.
Human drivers have an extremely long tail of idiocy. Most people are good (or at least appropriately cautious) drivers, but there is a very small percentage of people who are extremely aggressive and reckless. The fact that self driving tech is never emotional, reckless or impaired pretty much guarantees that it will always statistically beat humans, even in somewhat basic forms.
They do have approved third party body shops. Also mobile service vans. Not sure if this can be done via mobile service but in the past they’ve done things like computer upgrades.
SELinux: I’m sorry Dave, we don’t do that here.
I can almost guarantee you they are using it through a VPN or they have a western SIM card. If not I’d love to know what server they use, as I’ve tested this a bunch of times on several public and private servers and it’s always the same result. If it isn’t blocked on day 1 it will be blocked quickly.