Have you tried a bookmark? Or visiting the page a few times over the course of a week? I'm at the point where if I type 'ne' in my address bar it is the first autocomplete suggestion, which is convenient to say the least.
PG doesn't care about "SEO", nor about Google's "mainstream" traffic - because he doesn't want random people coming to HN. People who use HN regularly can write the site's name (Chrome even remembers it after you type it fully once), or bookmark it.
