Was thinking similarly, that it reads as though they couldn't plug these holes with software so there are a bunch of non vintage/obsolete Macs out there that are still vulnerable. If so, it would be nice if apple to explain thecountours of that vulnerability so that owners can take appropriate precautions.
1. Do not leave your computers unattended in public.
2. Do not let unauthorized personnel approaches your computers without supervision.
3. Do not boot your computers from unidentified USB device.
I'm serious. The so called "Dark Matter", as well as other firmware / bootloader vulnerabilities, can only be leveraged by direct access of your computer physically. So don't expose your computer to unsecured environment, even it's locked.