This exploit just requires physical, not administrative, access to the machine. You build an EFI "app", put it on a flash drive, and execute it from the UEFI shell.
indeed countermeasure like full disk encryption, computrace and Mac firmware passwords are all examples of things we do to raise the difficulty for a physical attacker.
BTW, I have physical access.
If you can get someone to run a USB that'll boot you open the user up to a bazillion exploits already and already own the machine.
I'm assuming that would probably need admin/root access to exploit, but it does mean that you can turn an OS-level privilege escalation bug into something substantially more persistent and difficult to recover from.