Truth is, every cached version I look at shows required as of December 12th. The document, according to the time stamp in the footer, was last updated on the 14th. Cyrus posted his tweet on the 14th, the date listed in the footer as being updated.
But again, the Google cache, which was updated on the 12th (so it was a snapshot from the 12th) shows required for author name as well.
The Wayback Machine doesn't give me much more information on this document, so I am not sure if the author name being required is new or not. I would suspect article markup would have to require author name. I mean, Google would want to know who wrote the article. But maybe Google did change it recently.
Cyrus is on the ball, so I suspect he was tracking this for some time and that it initially was not required and now it is.
Forum discussion at Twitter.
Update: John Mueller from Google told me this is relatively new. So nice find Cyrus!