Read the frigging articles. The reason this specimen is unusual is because it was protected from air and moisture. Some of the protein survived without being mineralized. Protein is not alive, even if it is a product of living things. If you have research indicating the rate of decomposition in the absence of light, moisture and air, please present your references.
Nuclear irradiation is the only thing that could preserve anything that long, even in a vacuum. The US Army commissioned studies on that subject in the early sixties.