I don’t really know that we have anything further to say then. A person who accepts the benefits of society but refuses to recognize a legitimate and binding obligation to that society is contemptible from an ethical standpoint.
A person who refuses to acknowledge his obligations has no ethics.
I disagree. I think someone can, for example, fight in an unjust war and still have ethics; they just have mistaken ethics. Although their behavior is contemptible and to be condemned in the strongest terms, they themselves are not contemptible. They are just making a deadly mistake.