I also have no doubt that prominent people who identify and are accepted as libertarian, and sites which are cited as and claim to be libertarian, have cultivated alliances with racist/nationalist/isolationist groups. To those groups, many libertarian positions are appealing: sweeping away all government regulation, for example, would get rid of those pesky laws that make it illegal to discriminate on the basis of race. Holding private contracts to be sacred and doing away with government interference in their performance means exploitative contracts -- close or even identical to actual slavery -- "entered" into on extremely coercive terms become perfectly acceptable. And so on and so forth.
It amuses me to see every article about the "alt right" define it as something different.
https://www.washingtonpost.com/news/posteverything/wp/2017/0...
It’s probably true that some of the overlap between libertarians and alt-righters can be explained by their companionship as members of the political fringe. But it’s not purely accidental, either. Historically, prominent libertarian thinkers have made the decision to cultivate ties with the nationalist far right, and have viewed racial demagoguery both as an efficacious political tool and an intellectually defensible position. The libertarian-to-fascist pipeline may have been forged partially by coincidence, but it was also crafted and maintained.