Wouldn't he be found at fault for not wearing safety gear, though?
Depends on the state. Not all states have helmet laws, and there is no requirement anywhere that I know of that requires any other gear. I've seen people on sport bikes wearing shorts, a t-shirt, and tennis shoes, going 80 mph (129 kpm).
Most states do have laws that reduce liability based on percentage of fault. In the case of the picture, if a fact-finder (judge or jury) decided the rider was 30% at fault because he was riding without protective gear, his award would be reduced by 30%. However, even if the fact-finder finds the biker was 99% at fault, the driver would still owe the biker 1% of medical bills. (There is no way to determine the biker is 100% at fault since the driver did rear-end the biker.) A few states have laws that say if the plaintiff is more than 50% at fault, they recover nothing, but not many.