I say just direct a Microsoft representative to his/her thread. Microsoft, the BBB and the seller's government can sort out the whole issue of legitimacy themselves.
That's kinda the problem though. They won't go for just the seller's thread. They'll go for the ENTIRE forum. And legally, they have the right to go for the entire forum. If I were selling weed on a website, the US government could take down the site rather easily. I mean, just look at megaupload.com and the whole kim dotcom thing!