No, it's not an administrator or mod.
It's that Microsoft troll, anonymac (user #96801).
When I tried adding him to the list, the name appeared without the check mark next to it. Nothing seems to work, I can't add him to the list.
Took a different user off my list, and re-added him, worked as expected.
(Edit: Never mind. It works now. Temporary glitch of some sort.)