[cyberax]

> the other is an external actor demanding what you do with your private property.

And why is that bad? You've just described a negotiation between two private parties. In any negotiation, parties try to get their counterparty to do something with their property.

Workers are negotiating with the company about the sale of private property that they possess (aka "labor services"). Of course, workers can also organize together, it's simply an exercise in free speech.

Heck, it's as libertarian as it can be.