As an aside, after qutie a few years in the bike business, I've only seen something fairly similar to this once. It was a rear, disc brake mountain bike hub flipped around to have the rotor mounting holes on the drive side, so that a six-hole fixed cog could be bolted on (like in the OP's pics), and no rear brake would be used. This was on a mountain bike, I believe it was a Surly Ogre with a rear-opening dropout, to be ridden on technical mountain bike trails. I thought the bike's owner was nuts for having a setup like this for off-road riding, but after knowing him for several years now, I realize that he just likes to try different things on bikes, and he's actually quite good at riding that fixed gear mountain bike on technical trails. We all laughed when he described hopping over logs on the bike, he said the biggest challenge is the position of the pedals at the critical moment. But, he said, "when it does come out right it's an amazing feeling."
My little story has no bearing (pun intended) on the OP's question, however.