Snapchat do certificate pinning for it's main API domain. I am not exactly sure why analytics domain are different and why not have certificate pinning. (I thought analytics go through the same API domain, but it must be wrong then).
The analytics domain was "sc-analytics.appspot.com" in which the lack of pinning is described at the tail end of the blog post.
From the OP, Snapchat started pinning not long after this program launched.