I've been using Google to find things on HN for a few years.

The file from January 2013 appears just as permissive:

http://web.archive.org/web/20130109093744/http://news.ycombi...

I have been too. I was surprised to find that HN didn't show up on Google a couple weeks ago. Yes, it looks like I was wrong. No, pg isn't changing titles because of SEO.