Blimey look he lands on his head! Aren't we always told by the non helmeters that cyclists very rarely land on their heads?
Yes, I noticed that. He actually lands just the way helmets are designed to land. This may be the rare case were the helmet did really save him.
But as to your point, so? Everything about this accident is rare. I certainly don't don my helmet and think "Good, I am safe now if a 200kg ruminant jumps on me", and I sometimes cycle in Richmond Park, so there is some risk.