While the leaderboard link does not work, I would like to point out that the site http://winterbash2013.stackexchange.com/ is still accessible, and that if you log-in the system still shows your obtained hat.
Since the data for your hat is still there, I would think that making the leaderboard work again would be doable (even if not cost free, we should evaluate the cost it would need and the load it could cause)
Update: the leaderboards are indeed still there, but the main link doesn't work, so you will have to jump to the appropriate sublink for the specific site. For example:
also notice that the meta site switch has broken the old meta stackoverflow leaderboard. It still somehow work but search or personal stats are somehow borked.
Also notice that pagination in the leaderboard seems to be misbehaving, so I would suspect that the sites are still there because they never took them down, not because they officially wanted to keep them. Older site for 2012 seem to be gone (used to be http://winterba.sh/ , now points to a page with some screens).
I conclude that the sites begin still online isn't something the staff really planned, so we should assume they could be taken down every moment. I won't be surprised if when the 2014 bash site comes up, the old one goes down forever. After all, it was intended to be archived: link here.
In the original intent of the question, I would say that we need an official statement from the staff. If an archive is to be done, it should be something they actually planned, not an half working forgot copy as the current one seems to be ^_^.