On the issue of hair; you know how Sikh have to cover their hair and thus have a turban; if you're totally bald, does that mean you still have to wear a turban?
I think it is more about not being allowed to cut your hair rather than having to wear a turban. And a turban just keeps all that hair tidy. Not many people are totally bald - even if people are balding on top, they still have hair on the back and sides, and they can grow that long, thus still having a need for a turban.
I'm sure if Duncan Goodhew became a Sikh, he wouldn't have to wear a turban.