Despite an established tendency by law enforcement of the era to turn to NSA for cryptographic assistance, it appears that the NSA’s prowess were never brought to bear on the Zodiac Killer who from 1963-1975 murdered at least seven individuals and taunted law enforcement with a series of encrypted letters that contained details of his case and, allegedly, his identity. In fact, this record is sole document released in response to a FOIA request seeking all NSA records pertaining to the Zodiac Killer.
As for the NSA’s blog post, it is a disappointment. Writing for a knowledgeable audience, it leaves cryptographic terms undefined. Also, there is little NSA- specific knowledge in the article. It’s just a brief general history post that could have been written by anyone with a basic familiarity with the Zodiac Killer case.
(1) See James Bamford's The Puzzle Palace, pg. 470-474