If this is true (or at least plausible to the relevant people), the author of that Twitter post will probably be on the radar of any shady government agency worldwide. Not a nice situation to be in.
The claims are well into the "I found a unicorn" territory, I'm tipping its either "If you misconfigure this, its unsafe", or its a real vuln, and its significantly harder to exploit that they are claiming.
That’s not all GNU/Linux though. Either the OP doesn’t understand a very common container OS, Alpine, doesn’t use systemd (also Void Linux and others outside the container space) or it’s something else.