I don't know how that works exactly... I had one of his, and this one, while they are very similar, this one has definitely had a bit of work done to it, and comes cleaner out of the box. The fact that its declared a Mystery Helmet pretty much sums up that nobody knows where it came from. Don't think you can really have a "domain" on a mystery. I think the MS, and BKBT Jango, are also reworked Mystery Helmets.
But thats just my opinion based from what I know about 'em... Which isn't much... lol... If I'm wrong about any of that, I'm sure that someone will correct me. Its just what I've gathered from skimming threads here on TDH.