Where do these Libertarians get off?
Free trade is a central tenet for the libertarians, free markets being the absolutely central pillar of the libertarian philosophy
Libertarians call themselves "classical liberals" and say, with a disgusting lack of modesty, that they are the true inheritors of the early American Republic, and what are hagiographically called "The Founders"
The first few months of the first Congress of the United States were almost exclusively a debate on tariffs. There was, I admit up front, an infintessimal bit of abstract lip service to the idea that, all other things being equal, tariffs ought to be low, yet the real Classical Liberals used tariffs to encourage domestic manufactures, tap the wealthy for their extra cash, and moralize.