Sounds like you already have the "defend your own stuff" idea in your head, why don't you enact it then? Can't be too hard to find out where someone on Deviantart lives. It's not Deviantart's responsibility to handle it unless someone makes it their responsibility.
Been there....[almost] done that.
Slightly different location.... Nullsoft....though it was publicly played out on the Devart forums....so, 'close'.
I pulled the plug when it was offered that an associate was willing to drop in on the miscreant's home adress [he was a neighbour - to her, not to me...I'm 10,000 miles away] - and she realised the error of her ways and the issue 'went away'.
People can be found.
As for my Architecture IP ....it's not on the net....so the furthest I've had to chase it was the distance from my place to Queensland. In that case it was a Lawyer trying to claim my IP....
RandomEasyPlayer.....exactly....how DOES that work?
I think I'd prefer to pay someone to 'make' them cease their thieving instead.....