Their references fail to support all their statements. For example from the introduction, "In addition, "natural history" studies of free fall indicate that failure to take or deploy a parachute does not inevitably result in an adverse outcome." Chasing down the reference for that statement points to the case of Vesna Vulović. According to wikipedia she a) was in a plane at the time of impact which will exhibit significantly different freefall characteristics to the human body and b) she "suffered a broken skull, three broken vertebrae, one crushed completely, and was in a coma for 27 days" which to me would be an adverse outcome.
Further studies are clearly needed. I suggest animal studies in pigs.