Really? Let's say you're a loyal reader. You have him RSSed, and you get excited whenever you see his posts show up in your feed reader. How would you feel if after a month or 2 you said "hm, Alex Payne hasn't blogged in a long time, wonder what the deal is."
You go to twitter: "@al3x why haven't you been blogging recently?"
"@you I decided to stop blogging"
Wouldn't you wish he had written one final blog post letting you know instead of waiting for people to figure it out?
To an outsider who just sees his posts occasionally on HN, it may seem dumb, but it makes more sense for his loyal readers, I assume.
A lot of HN readers and empathize like so: what if pg "just stopped" writing/publishing essays. Wouldn't you wish he had at least written one last amazing essay describing his rationale for stopping and letting everyone know?
The real WTF, as they say, is that this would shoot up the HN main page. It's good for his loyal readers that he makes a conclusion posts, but there's not really a point in posting this on HN so that people who don't read his blog can know.
And my advice to you about giving advice: Explain why he should do as you suggest. What's in it for him? What's in it for you? The tone of your comment, espcially the "thanks" at the end makes this seem like a request for your benefit rather than a suggestion for his benefit.
Is that the case? If so, you may find it more effective to explain why his blogging about stopping blogging is harmful to you. It may be that another solution presents itself. For example, if you aren't subscribed to his blog but are annoyed to have this post taking up space on HN, perhaps the solution is to appeal to HN readers not to upvote this kind of post rather than to appeal to the author not to write it.
Likewise, if there's something in it for the author, explaining that will be a lot more effective as it will appeal to his self-interest. He explains quite clearly that he writes the blog for himself, not for you or I. Therefore,he presumably has already decided that this post is a personal benefit for him. If you can think of a compelling reason for him to eschew such a post, it's best to tell him so rather than making him guess.
That way you will get what you want by helping him get what he wants. Win win!
You're barking up the wrong tree. It's unlikely that 'the next person that wants to stop blogging' reads HN (yes I know about spolsky and al3x). In response to this story, you could ask us not to vote for such stories or even urge us to flag it. Although such metacomments are discouraged, it's still more useful than wildly addressing a bunch of people that probably won't be reached.