Ok. So by "thread matches," you mean threads with the term in the title? I have no problem with that because to me, having the term in the title is the same as having it in the post. (And I thought you *already* included all threads that had at least one post containing the term. So this change seems unnecessary?)
What I don't like is the threads with the term in their titles always grouped at the top. This is resulting in very old matches at the top, which is counter-intuitive when I have my sort order set to "date."