Defense involves violence and you want to avoid it if possible. So he advocates focusing on protection. As I have frequently heard Philip Jacobson argue, there are great incentives to avoid violent conflict. War is costly. If it starts each party tries to destroy the valuables of the other.
War is a negative sum game.
Whereas peace with free trade is a positive sum game. We can normally expect potential antagonists to be willing to invest heavily in avoiding war. For instance a private security company will emphasize restoring stolen loot to its owner, the customer. Whereas a government agency on learning of a theft emphasizes catching and prosecuting the criminal, and sees the loot only as evidence to be guarded and not as property to be returned. And as Bruce Benson recounts, government agencies are so intent on doing their thing, prosecution, that they treat the victims of crime not as customers to be served, not as people who need help, but as evidence to be presented at the right time in court.