I think a lot of people here have an anxiety about the regrets they may have if their life were to suddenly become very finite. The article is the testament of a man coming to these realizations, and we are here to discuss the themes involved.
The guidelines explicitly say "Please don't complain that a submission is inappropriate" (the recommended action is to flag it or email the moderators), and it's the convention on HN to flag comments/posts that break the guidelines.
It's also unwelcome on HN for there to be "that person" who sullies a discussion involving personal reflections about life and death and other profound human contemplations, with a curmudgeonly comment complaining that it doesn't belong here. To be fair, someone always ends up being "that person" on every such thread, but it gets repetitive and predictable, which is why people are quick to downvote and flag.