His words are clear. Agreed, he wasn’t a libertarian himself just as I am neither an actor nor a politician. He did, however, define libertarianism as the heart and soul of conservatism.
Good god man, read the damned quote.
Taking the 1975 quote out of context of the rest of the interview, it to be selling a lie.
Besides, it was his way of reversing it to the libertarians, first he tells them that they should embrace conservatism, and then he explains why they are misguided by refusing to do so.