I'm not an expert in the field, but I'm pretty certain the writer of this piece is neither. He is not using correct units and seems to be misusing the term "fat

I'm not an expert in the field, but I'm pretty certain the writer of this piece is neither. He is not using correct units and seems to be misusing the term "fatigue strength". The proper way of conducting this kind of material comparison would be finding the design limit. In this case it would be probably either toughness/weight of fracture toughness/weight. Then if you are unable to come up with specific grade of metal that simply beats bone, you have absolutely no case. Typically alloying for high strength decreases both toughness and fracture toughness.