Catherine,
1. How do you define “voluntary action” and which part of the quote is incompatible with it (and how)?
2. If by “voluntary negotiators” you mean private dispute resolution firms, then this is a perfectly valid service to offer on the market. If memory serves, Peikoff mentions these approvingly, along with hiring private security, in a lecture or Q&A (either the 1976 lectures upon which the book was based or the advanced seminars he gave around the time of its publication). However, if by “voluntary negotiators” you mean that private firms should entirely replace the government, then the problem with that “solution” is baked into the very phrase “voluntary negotiators.” The purpose of objective law is to set objectively defined boundaries between people, such that one cannot legally violate the rights of another, even if the violator does not care about or recognize those rights, including rights a person gains via contract. But if negotiations are merely voluntary and a person may decide either not to negotiate or not to carry out whatever the mediator rules—if there is no backstop for addressing rights-violating actions, the result is an unjust society that does not uphold the principle of individual rights. Because such a government does not extract force from social relationships, it also fails to create the conditions for a free market: A free market is one in which rights are respected and protected. Those who advocate that society, as a matter of policy, replace objective law courts with “voluntary negotiators” on the premise that “free markets are better than governments” are thus working with invalid definitions of both terms. Free markets only exist where freedom—meaning, individual rights—are protected by government.