Why is Vitali fighting this bum Johnson?

I know he suffered a shoulder injury but it was a little odd. Yes he had a problem with his rotator cuff but there were only a few rounds to go. And yes he was technically winning the fight comfortably (on the scorecards) but in reality it was a close fight. I mean he was fighting 7 months later, tough to really know how serious the injury was.

I just don't know about Vitali's durability, moreso then his toughness. I'm not sure he can get through 12 rounds against a real opponent at his age. His retirement in 2005 was due to mounting injuries. Of course as the landscape of the heavyweight division was/is still poor he couldn't help himself in coming back but I struggle to see him reigning for too much longer.