I might not think it was a bug if in the door's description it didn't specifically say they it doesn't allow wild creatures through.
This drecko went through this door as well as three other manual airlocks to get to this point. Though I really didn't want to, I had to kill it because it continued to get into this and the other farm and ate the plants while my Dups starved...
Steps to Reproduce
Have wild creatures locked out of an area with a manual airlock. Eventually they will navigate through the doors while your dups go about their work.
This issue has not been confirmed by a developer yet.