I guess he only likes to wear a helmet on the football field, and not on motorcycles.
I remember during an annual helmet law protest in the DC area the news media reported something to the effect of...
"Motorcycle helmet law protester crashes, but helmet saved his life".
On a biker board earlier this year I read a posting about a rider in Connecticut who was thinking of taking off his helmet while riding on a quiet country road with no traffic. While making a low-speed turn at under 5 MPH he lost his balance and the bike tumbled. His head snapped against the curb putting a crack in his helmet. Needless to say he doesn't think about riding without his helmet anymore.