The old threads are because when I deleted them, they were not actually deleted. I changed their IsDeleted value from 1 to 0, even though it was a computed value in a union or some stupid crap. It was a pain.
Basically we had about 3500 posts deleted, but were still stuck in the database. I figured, if I have to store them, why not use them?
That's why those look weird with no last post message or what not.