That Santa image is a joke made using photoshop.
Using reverse google image search, there are only 4 places the image exists; here, tumblr, and two from a nyafuu archive. None from an official source.
Reading through the nayafuu archive, there's a version without the shadow figure. It was also posted in response to a somewhat recent pic of Greg, and they match perfectly.
The version with the shadow figure shows up after the original without it.
All of that happened Nov 25th - 27th.
When did the leak containing the new piece show up? November.
They used an existing image of Greg and a leak with new parts to make a joke image, and people too diluted to know better have spread it around as proof.