Winer is not using the example of Jobs to refute the idea that younger people are good at startups. In fact, he acknowledges that younger people often have the willingness to accept risk and enthusiasm that their older counterparts may not have.

He's trying to refute Wilson's idea that younger people are developing the design patterns of the web while older people are used to reading the newspaper, watching TV and generally out of touch with what's going on with technology. Steve Jobs seems to be a pretty good example of a person whose ideas about technology have improved with age.

In any case, the idea that the average twentysomething is more plugged in than the average fortysomething may be valid, but it should be obvious that the situation changes when you are comparing individuals who are interested in and devoted to technology development.