The fundamental question here is whether the landscape of attainable levels of liberty has no local maxima, i.e. whether an investment in force initiation could ever lead to a net reduction in the overall incidence of force initiation. I, too, wish that theft didn't exist and the strong never preyed on the weak and that coercive taxation were not necessary and that every child had a pony. However, I just don't see any sticker on the store packaging of this universe that guarantees that all ethical judgments inside the box involving political theory have to be simple ones. Nobody can certify for us that for the tool-using speech-capable pair-bonded omnivorous bipedal primates on this planet, it just so happens that 100% absolute abstinence from force-initiation is always the optimal strategy for minimizing the net incidence of aggression in the societies such primates form. I can take very seriously the detailed consequentialist arguments of a David Friedman for advocating such abstinence, but I see very little merit in simplistic deontological arguments for it.
It's obvious to me and to most Americans that aggression will never end up minimized if liberty-lovers simply promote aggression abstinence through the example of their chastity. I'm a libertarian, and so I value the actual real-world protection of liberty — i.e. the minimization of aggression — over maintaining the non-coercive purity of my white-gloved hands. I value the actual protection of real-world liberty over its sacrosanct hypothetical inviolability. The child and her doctor both seek to minimize her pain, but only one recognizes the necessity of needles.
Many minarchists would say that the general right not to suffer force initiation is not absolute and in fact can only be well-protected using certain constitutionally-defined kinds of coercion that Rothbardians would call force-initiation. These minarchists might cite some combination of
- enforcing a due-process-observing monopoly on retaliatory force;
- the right of the accused to subpoena witnesses and enjoy an impartial jury;
- prevention of free-riding on the provision of protection from foreign invasion and universal access to the justice system;
- policing of forms of aggression (e.g. pollution) too distributed and cumulative to allow tort-based prevention;
- collection of the ground rent of exclusively-possessed land, in order to compensate those excluded from it.
For such libertarians (like me), the assertion that force is being initiated is not always an argument-ending trump card. If I have to choose between minimizing the real-world incidence of aggression and accommodating some anarcholibertarian's desire to have what he thinks is a clean conscience, I'll choose the former every time. As a grownup, I recognize that this universe has not arranged itself so that the optimally moral political choices will always be obvious and always be guaranteed to to never blemish my hands or trouble my conscience or have any possibility of direct negative consequences.