(Warning: the poem read at the beginning has swear-words in it. Just the poem; no swear-words in the interview.)
Whether or not you agree with everything said (I agree with a lot, but not everything), one thing is true: a group that does not produce a lot of offspring does not survive. Hear that, Europe? Or, as I once said to Rabbi Posner (a father of twelve kids) when talking about the Hareidi-MO machloikes: "If they can't convince them, they'll out-breed them".
Not to mention that each child is a blessing.
By the way, my wife didn't get the context of the interview fully, so I will explain it for the audience. Libertarians believe in the concept of non-violence. That is the basis for their political beliefs (they don't hate taking money from the rich to give it to the poor just because it's a stupid economic and sociological policy, but also because it's an act of violence), for their social beliefs, for their educational beliefs and, apparently, for their ideas in parenting.
So, for instance, my wife told me of someone who found about the areas that her kids were not interested in and forced them to excel specifically in those areas, arguing that that would develop them as much as possible, teach them discipline, willpower and going against the current. Whether or not I would agree with this approach (probably not, even though I believe in encouraging one's kids to do such things in certain areas of life, more micro than macro), Libertarians certainly would not.