It's literature, and SF, so it would be a mistake to take the quotation too literally. But since we're here; the thing to remember about Heinlein is that he was a romantic and a futurist at the same time. Hence his militarism wasn't so much about the enemy as about providing an opportunity for romantic heroism. Similarly with the other items in the list. It's not grounded in practical necessity but in a "renaissance man" / hero of a novel approach to being able to not just handle situations but show off in them.