I think you're reading it as "Unfortunately, moderators occasionally unkill such threads..." when it's meant as "...they tend to be flagged to death by users regardless, unfortunately".
True. But the following phrase is set off by both a period and a set of parentheses. I think it’s pretty clear the author’s intent is for there to be a complete sentence about the behavior of HN users and then a complete thought saying that was unfortunate. (Then a parenthetical about the moderator behavior.)
