OK now I see what you're saying.
yes tumbling was taught in school in the 70s when I attended a PSS.
More was taught to me in martial arts training on 'how to fall properly when thrown around"
However, unless your friend was wearing a teardrop TT helmet (see:Garneau Rocket or Chrono) when his chin was tucked to chest, his head wouldn't hit the ground, nor would a helmet in such a position.
Now if he'd fallen HARD, his head would have snapped back from the sudden deceleration anyway, and he'd stand a stronger chance of both head and spinal injury from that impact without his helmet on, as the helmet once again would absorb the impact of his head hitting the street.

statistics are good sometimes, but so is a sound medical knowledge, and likewise an education in engineering or science. Either of the latter two involving extensive physics matriculation.

Thank you for allowing this to remain a civil discussion. I bow out when it becomes too passionate.