The Founders, at least many of them, were personally conservative in behavior, but of (classical) liberal opinion about the role of the state. A sound position, IMHO. Remember, the Founder were almost all deeply versed in both English history (including Magna Carta, Henry VIII, Bloody Mary, Gloriana, the the debacle of the Stuarts and the Commonwealth, and the Glorious Revolution. The understood that liberty involved responsibility. Moreover, almost all of them were classically educated and deeply imbued with what were seen as the virtues of the classical Greeks and (especially) Romans. Many of them were deeply committed to the notions of 'civic virtue' - a willingness to voluntarily subsume one's own interests to those of the state for the greater good. Think of Horatio at the Bridge (in Macaulay's telling) or Cincinnatus at his plow (in Livy).
I think this is the great flaw of libertarianism. The libertarian over-simplifies human nature, natural law, culture and society, family, church, and all that makes a nation a nation, and force their own analysis into the box of recognizing only the premise of the individual right to choose without any other factors or considerations recognized as legitimate. They reduce their own argument to an absurdity. It makes otherwise normal, moral, and sane individuals raving idealogues.