Looking at the screenshot, it is probably a WB that Stardock commissioned Rennie to do for them to sell and they never released it is all. Thinking back, I vaguely remember other situations like this, skins designed by artists for companies, but sadly never released.
Heck, back in the old days I was commissioned by two different companies to design XP visual styles for them to sell, but unfortunately one went out of business and the other went the way of packaging their downloads with evilness.