Well, it doesn't necessarily mean it's bungie. While they could be doing that, it could also be forum users. Some will get moved because they are duplicates and triplicates of the same post and that's all Bungie, but a good chunk will get downvoted a few times and be moved out of trending and highest rated. I wont pretend to know how the forum rules work for moving posts to and from those two lists, but from what I've seen the minute one or two people downvote a thread, it moves out of both.