Kids who wish to follow in a famous athlete's footstep will think that anything this athlete does is acceptable. However, I think that this particular case can be chalked up to nerves since it was, after all, the Olympics. I don't think kids are going to think that it's a good idea not to sleep but that he was nervous and couldn't sleep. If Michael Jordan has a history of not sleeping before big events then kids will think that sleep is overrated and they don't need to get good amounts of sleep because "Michael Jordan didn't."
Famous athletes with poor health habits sets a bad example for kids. Young kids are impressionable, and if a star athlete performs well while engaging in poor habits, it sends the message that they can also do it. In this day and age, with limited privacy, actions are well publicized.
Many kids look up to athletes, and if they know about things like this, they might try the same things. That does not mean that athelets have the responsibility to be role models, just that is important for parents to pay attention to who their children look up to and what kinds of behaviors they are copying.
Children have plenty of bad influences, to the point that they are no longer even influenced by athletes. They are also a lot smarter than we give them credit for. They won't go doing whatever athletes do. They copy their parents, who are even worse influences. We can't fix it.
Michael Jordan had many good habits that rubbed off on kids who admired him. He worked hard. He did not give up when he was cut from the Varsity basketball team in high school. Most of the time, athletes model healthy eating, sleeping and living because that is the only way to be a successful athlete.