@maciej
How, exactly, does your novel interpretation of Rothbardian ethics play out in practice?
I mean…
What if Bob and Alice are walking near each other, and Alice accidentally stands on Bob’s foot, causing him minor pain and trivial injury. Is Alice now a non-person vis-a-vis Bob forever more because she negligently hurt him in some tiny way, thereby violating the NAP in an absolute sense?
What if Bob and Alice are talking, and Bob says something she finds really insulting, so she slaps him and walks off. Is Bob entitled to unload a shotgun into the back of her head?
What if Bob and Alice are talking, and Bob’s breath smells really bad…
How are third-parties supposed to react to these goings on? If arbitration based on the NAP is impossible, because the NAP flies out the window forever more as soon as somone violates it in the most miniscule sense, aren’t we just going to have a completely ridiculous and lawless situation?
Are you sure you agree with Rothbard? Most people who assume such a distorted interpretation of his ethics are quick to reject libertarianism outright, and I can’t say I blame them.
The NAP is not some sort of social contract with a unilateral cancellation right afforded to its parties in case of any breach, no matter how minor, by another party. That’s the contract the state pretends it has with its subjects, except it is the only one with a cancellation clause available to it. 
The NAP is a principle derived in terms of natural law. It continues to apply at all times, even against people who do not comply with it in an absolutely perfect sense in the way they treat you, which is just as well, because NO ONE is capable of abiding by the NAP in a perfect sense for very long. This implies that justifiable private defense is the only form of aggression allowed in terms of it. Aggression which unreasonably exceeds that which is necessary for private defense, under the circumstances and concerning the threatened property in question, is therefore a violation of the NAP anew.
If there’s no place for arbitration, there’s no reason for us to talk about ethics. We might as well adopt total, solipsistic egoism and go around doing whatever we like to others if there never actually comes a time to justify one’s actions to others in terms of ethics. Why bother deriving property rights, if the fact of a property rights violation is just something people can make up whenever they like, and are never expected to demonstrate to 3rd parties, or have decided by 3rd-party arbitration? Why not just allow people to act in terms of their impulses and leave it there?