Finding Jobst quotes on helmets is hard. One must access a search engine and type in both Jobst and helmet. Here's the money quote:
“I avoid helmet discussions because they are a religious belief. There are no realistic tests and all the people I know who crashed with one received severe head injuries as bad as if they had no helmet— usually skull fractures in the face. In contrast, I and my fellow riders have crashed often and not gotten head injuries other than a scrape that drew a bit of blood.
As I pointed out, Muhammad Ali's glove has far more cushioning than a bicycle helmet, yet it was possible with a mass far less than a human skull for him to deliver knockout punches, protection against which the bicycle helmet is touted.”
With abandon,
Patrick