I agree. Absorbing 100 J (the paper's assumption) over an entire 75 kg body would be ~1.3 Gy whole-body dose, or 1.3 Sv for photons. That would probably make you sick. Traditional radiation therapy for cancer delivers 2 Gy/day x 30 days to the tumor to kill it.
What if mysterious illnesses like fibromyalgia are just PBHs? Hmmm...