Fully agree, allotmenteer, that is one reason why I was interested.
Another reason for my interest is that this type of injury is a fine example of how most of the body is unprotected when a helmet is worn, (and they provide very little protection, if any, even for the area they cover).
I wish all those, particularly non-cyclists, who succomb to the propaganda about helmet wearing would just do a simple plain-sight observation of the helmet wearing cyclist, and note that in fact 95% of the body is not covered by the helmet. The uncovered part is vulnerable to very serious, life-threatening, and often life-long, injury eg, ruptured spleen (bleed to death in 20 minutes), crushed pelvis (impotence, infertility, permanent catherisation), broken limbs (impaired movement, arthritis, etc).
For those who prefer to do their observation from the couch, there is a commerial currently running which features a full frontal of a very attractive female cyclist with the upper part of her head encased in the usual plastic bowl: her body looks so vulnerable to the following motor traffic that I have been unable to notice what is actually being advertised.
My second interest in this case is whether a helmet increased the rider's confidence so that he sped down the hill faster than he would otherwise have done. Such confidence is entirely misplaced given the evidence from analysis of cycle accidents where a helmet was worn and the precise speed at point of impact was ascertained. Such evidence, when heeded, soon destroys any confidence in the efficacy of helmets which may have come from purely anecdotal accounts along the lines of "I was going at 30mph, and my helmet saved my life".