The author makes some good points in this article.
Excerpt:
But the Founders also believed that if social order is to avoid degenerating into tyranny, we cannot allow politicians to be our moral guardians with the power to bludgeon society’s sinners into obedience. This is because, as Madison so wisely observed, man’s nature is not angelic, but forever flawed. Because it is such, allowing politicians to act as moral guardians of society through the coercive arm of the state is fraught with danger.

Therefore libertarians maintain that virtue must be freely chosen, not legally mandated. The linking of society’s moral guardians to the coercive arm of the state during the Middle Ages created enough evil and cruelty, that we should be cured forever of such a temptation.