There's only ONE James Möbius, and I'm HIM. (to paraphrase Wally Wood).

My foe has been half vanquished anyway. the account he created using my name and art has been deleted by the admins, as has the very nasty one he created to try to intimidate me, and others with. It took a bit of doing, but DMCA reports get attention. If someone is posting your work without your permission on this site, you can expect them to address it quickly, but 3rd party reports just don't get the priority they deserve.
    I don't think they're lazy, they get 10,000 new deviations every day on average. they just don't have, and can't afford the manpower to monitor it all. in retrospect I'm impressed they responded as fast as they did to my situation. In this case, with all the evidence, even without complaints from outside, they really should ban his IP and kill those 2 other accounts. I really don't think they will though. Ce la vie. crime pays. I spend my whole life trying to do the right thing, watching other people steal, cheat and lie, and get away with it, and get ahead in life, I try to do some good and get hours of wasted time combating an internet troll who's trying to tarnish my name and get my goat. I have better things to do with my time than try to protect the intellectual property of high end porn websites who can't even be bothered to file complaints themselves when you send them links to infringement of their work. pick your battles, kids. It's almost enough to make you jump ship and make money the easy way. I'd rather sleep with a clear conscience. and plagiarists, don't steal from starving artists, if you're going to steal, steal from the rich. thanks.

"Thank you for contacting deviantART, I will be assisting you with your support ticket.
The content which you have specified has been reviewed and removed by our staff and this member has been issued a written warning and advised of our copyright policy.
Please contact me again if you need any further assistance in this matter."

UPDATE: the admins have in fact deleted that person's remaining 2 accounts, which were full of pictures stolen from other websites, and banned the individual, if temporarily, from starting a new account. I imagine they could fake an IP address and start a new one easily enough anyway, but at least it shows that it pays to report wrong-doing after all, when you see it. my faith in this site is restored.

PS I've lost count of how many new followers I've gained as a result of this ridiculous situation! so thanks! I've seen a lot of nice art I never otherwise would have, and made several new friends.