I'm fairly sure that his changed appearance is not the result of corrective surgery to fix a boxing injury. He's had bad cosmetic plastic surgery, that's all there is to it.
That said, Rourke's career is FAR from over.
He's more in demand now than he ever has been, including his stints in the "Expendables" franchise, as well as his roles in the "Sin City" movies. He's everywhere nowadays.
So whether boxing in Russia is a smart move or not, he clearly isn't doing it because his career is washed up. He must truly just love the competition of boxing.