On the one hand, Barack Obama, speaking as a dad, says he "would not let my son play pro football." It's a reasonable judgment, one other parents have made and one they're entitled to make (though enforcing it on recalcitrant sons is another matter!).
On the other hand, President Barack Obama believes NFL players “know what they’re doing” and understand the health risks of football. As president he makes the reasonable judgment: “At this point, there’s a little bit of caveat emptor. These guys, they know what they’re doing. They know what they’re buying into. It is no longer a secret. It’s sort of the feeling I have about smokers, you know?”
So Obama seems to understand that the fact that he would personally ban football for his hypothetical son doesn't mean football should be banned for everyone. He seems to understand, in this instance, the distinction between the (many) judgments an individual and family should be entitled to make and those (few) rules political authorities should seek to impose. It's a distinction crucial to a free society. It's a distinction deeply embedded in the American psyche. It's a distinction that requires Obamacare be repealed, and explains why it will be.