Yes, this is exactly how it worked. It sounded good in theory, but in practice wasn't that great IMO. By only giving a few random users the ability to mod up/down posts, for a limited time, and ONLY in threads they didn't post in, there just wasn't much incentive to moderate. Personally, I frequently got mod points, used them, and then wanted to respond to something somewhere else in that thread, and so making my post would undo all my moderations. It was a choice between my speech being stifled, or being able to do my civic duty of moderating, and I chose to exercise my speech most times, so I probably was not a very effective moderator. Perhaps if they had made it more fine-grained it could have worked better (so you can't mod in a subthread you post in).