Truthfully, Senor Alvarez isn't much of a character, and we can't really say much about him besides that his office has a rockin' view of the sunset. But the story he recounts provides an important balance to another character's story, that of one Breckinridge "Breck" Scott.
Scott's story details the horrors and evils of capitalism, since he uses the capitalist system to basically sucker millions of people into giving him millions of dollar. But Alvarez's story provides a counter account of capitalism and its benefits.
When the Yankee refugees haul butt to Cuba to escape the zombie hordes, they unknowingly bring with them a huge work force. To drain the refugee camps of the teeming millions, the Cubans let the refugees work various jobs. This act builds up Cuba's work base, allowing the country to expand and bring in more money. Cuba becomes the "breadbasket, the manufacturing cent, the training ground, and the springboard" of the world (7.6.22).
As the money flows, the middle class grows, and with it, comes middle class values as the Northcubanos integrate into Cuba society. This creates a bond as the Cubans are introduced to "freedom, not just in vague, abstract terms, but on a very real, individually human level" (7.6.23). What we're seeing here is the novel's argument for the upside of capitalism.
Capitalism brings in unheard of wealth for the Cuban people. As it does, the Cubans unite toward the common goal of maintaining not only that wealth but also the freedom to pursue and do what they want with it. This freedom evolves into a desire for a democratic system instead of their current dictatorship. With democracy comes true freedom as well as strikes, protests, special-interest groups, political parties, election season, and—of course—lawyers. Hey, you win some; you lose some.