It's 100% a joke. The US government doesn't drop a giant jpeg on your domain if they seize it for copyright infringement (anymore) unless it was selling copyrighted material, and when they do, they don't make a custom image advertising which companies filed claims against you, there is a standardized notice.
Also if you go to pages other than the home page, they're still up; they just removed all of their manga, with two exceptions which were added today.
One is a fix for a chapter of a yaoi manga (that's looking pretty good). The other is fucking "Truck-kun".
tldr: I think they're fine guys.
Also I'mma be livid when they put everything back up and my entire follow feed is unread.