You're right! Sorry it's late at night here, and I guess I'm more tired than I realised.
But how can I go to sleep while Dean is missing?

Just a thought: Could Antonin have thought Linus was behind the original breakin?
After all he knew about the instruction to steal. If so it might explain why he wasn't more than a little worried at the time. He would trust Linus to not take anything dangerous.
Because otherwise, having had one attempt on his office, I am surprised he wasn't using more active wards.
I remember Sinistra using one that turned eyebrows purple. And I think she said she hadn't liked Antonin and Razs more radical suggestions, so he clearly has some strong ideas.