In Heinlein's story "The Man Who Sold The Moon", a businessman threatens to put a corporate logo on the moon ... in order to get a rival company to bid higher to keep the moon un-logo'd.
Free markets can't exist without enforcement of rules against violence and fraud. Without such enforcement, race-to-the-bottom effects mean that employment devolves into slavery and all markets in goods become dominated by "lemons" (fraudulent goods).
An actual free market in labor requires limits on what a powerful employer can demand from workers. An actual free market in goods requires protection of customers from fraud, and arguably also from monopolies. Both of these require something like a state, an entity empowered to intrude into other people's business in order to enforce rules.
Even starting with anarcho-capitalist principles, consistency ends up endorsing a minimal state: see Nozick, Anarchy, State, and Utopia. (However, Nozick's path is not the only path by which a state-like entity could arise; rather than from 'protection agencies', we could imagine it arising from labor unions or cooperatives instead.)
In gist, "freedom isn't free" — if you want to have a free market in labor or goods, you have to have enforcement against those who would deprive others of freedom through force or fraud.
Kaczynski was not an anarcho-capitalist, in any event, but an anarcho-primitivist — whose beliefs led him personally to commit murder, and who endorsed the mass murder of almost all humans. It's worth noting that Kaczynski was also arguably manufactured by psychological abuse; he was a gifted mathematician until he became the victim of an MK-ULTRA program.
In today's example of a garden path sentence ....