It's not something that I imagine many folk will have a use for I'll give you that!
As for myself it wasn't wanting threads to be at the top of a forum it was taking existing threads and needing to reorder posts within them, specifically in my case to add a post at the beginning to display differently (like vb.org does with hacks), my solution was to edit the datestamp of the post so it becomes first post - that again I doubt more than a couple others would ever need but still, sharing is good