I don't think so. The liberty movement is too disorganized to qualify. The Libertarian Party? Don't make me laugh. They are terrible at recruiting and retaining members. They are famous for schisms and infighting. Maybe they'd like to be, but if so they haven't done their homework.
To me a cult is characterized by a rigid hierarchical leadership structure, secrecy, an us vs. them culture, and emphasis on recruiting and maintaining members. This varies.
Are libertarians cult-proof? I doubt it. Interest in Libertarianism means that a person tends to be idealistic and interested in abstract arguments. These sorts of things a big part of the bait that cults tend to use. Someone who wants to do the right thing and change the world may be persuaded to join a strange group, sever contact with family and friends, and donate time and money to a worthy cause.
Doomsday cults want to survive the end times. Some will sell you self-improvement (scam). What sort of cult would people join willingly? 7 tactics of coercive mind control