So yes, if your entire town decides to blackball you, that is an exercise of their freedom. If people decide not to sell you their property, that is likewise their choice. You are just as free as you have always been, no one is using force against you. They are simply refusing to cooperate with you.
In what world does forcing a person to employ another not an impingement of their freedom? Anyone who can use the threat of violence to compel participation is a master, and free people have no masters.
> Suppose you live in a society that makes collective decisions by voting
As long as these decisions cannot be enforced with physical violence then you are no less free by being excluded. Say I run a supper club which votes on where to eat next, are you less free by not being invited?
> If a group of people kill one of your neighbors for violating some extra-legal rule...
This entire paragraph describes corruption, which is inevitable, and does impact your freedom. No human process is immune.
> Is chattel slavery an imposition on the freedom of the slave, if physical violence is not used?
Chattel slavery is defined by the use of violence to confine the slave literally in chains. If the slave can just leave he's not very enslaved is he?
> there are plenty of restraints on your power to act and speak that do not involve violence
Most of these take the form of the threat of withholding cooperation. This is a perfectly legitimate threat to make in a free society, and one I contend has no bearing on your liberty. Living in a free society is merely agreeing to coexist peacefully, not that everyone must cooperate, or be the same team, or be immune from the consequences of failure. In fact, my reading of the article is that it means exactly the opposite - that people are free to cooperate or not as they see fit.
