Actually if you read around it does look like he was fired. His mom (yes she has a DA) said he didn't willingly resign and the impression I got was that one of the other staffers wanted to make some changes to the site (go to SpyEd's journal - he's an admin, and he's talking about some changes) and Jark had a disagreement. DA are also deleting journal entries that involve this matter.
http://strony.aster.pl/drsaq/comment.htm This was deleted
I've also seen a supposed (key word there) email from one of the other admins of Deviant Art who talks about how Jark might pursue legal action and how SpyEd wants to take control of the site and turn it into more of a corporate thing.
But yeah. If you look around, it really looks like he was fired because of a disagreement with the other staff, most likely SpyEd.
I don't think it's a publicity stunt, I think they've really fired one of the co-founders of the site, and personally I think that's really sad, regardless of what people think of Jark.