I pinned it. I usually do that for more boring reasons, like linking to a previous submission when an item is a dupe. But sometimes there are admonitions like https://news.ycombinator.com/item?id=23158853 from a couple days ago, and https://news.ycombinator.com/item?id=22827249 from a month ago, that try to steer a thread in a more guidelinesy direction. That works. But I try to do it sparingly.