It's not a hoax...it's been published and well-documented, tho I am not clear on the details. The main thing tho to keep in mind is that it is not at all inherently impossible for such tissue to be preserved. That anything is preserved at all is an accident of the conditions in which the organism has been buried and decayed. Most organisms are not fossilized at all. Yet, there are some well-known examples of fossils in which soft tissue is frequently preserved....insects caught in amber. Here, the soft tissue is preserved because of the properties of the amber itself...it has just the right kind of stable conditions to allow such tissue to be survive decay even for millions of years. To consider whether it is "impossible" for certain tissue to remain "unfossilized" in bone, again we need to look at the specific circumstances in which the bone came to be preserved. To answer that, one would need to discuss the geology of the site, ancient climatic conditions, and so forth which would bear on preservation of bone. As far as I know, such matters are still not fully understood.