Doesn't appear to be flagged, has 19 points. Most likely it fell through on point/new-ness(age) and dropped off the front page.

I believe new posts are weighted a bit higher - but there is also some threshold going from "new" to front page. This appear to me to be a typical "almost interesting" (as judged by up-votes) - made it to the front page, but then got overtaken by other posts.

Ed: the current code behind hn isn't open source, but it might still resemble this to some extent: https://github.com/arclanguage/anarki/blob/master/apps/news/...