not downvoting you, but searchengineland is actually a very good/reputable site. It is very believable that the original submitter found this out through them. (IE: this isn't spam)
What value does the link add? Which URL has more information? Should all of HN go through this blog to read the actual information? No. It's blog spam.
The value, in my opinion, comes from the fact that SearchEngineLand broke the story. The original Google post is extremely low key, as one might expect given that previous versions of the document were leaked not released with an accompanying announcement.
As best I could tell, no other outlet had covered the document release before SearchEngineLand nor had anyone submitted the original to HN.
As an aside, what else can one expect visually from a site devoted to SEO?