It should be able to be set at the node level, but for some reason it's not working.
EDIT: WAIT... I think I see what you're saying. That's a sub-forum and it's inheriting the parent forum's setting. That is a restriction from XenForo itself. I can't change the way that works. But I will ask Chris to re-visit that problem.
Still running into issues with members not being able to edit their first post thread title so they can mark their ads sold using the Thread Status add-on.