I take your point, but we're dealing with two different "values:" there is the value of the shares as traded on the stock exchange and the value of the fund's holdings. You seem to think that there is a direct and absolute correlation between the two, but that's obviously not the case - witness the fact that I am up around 30% in a few months time, and the only thing that's changed is the continuing improvement in relations between the two countries.
The thesis is simple: the fund's share-price responds directly and proportionately to changes in Cuban-American relations. As those relations improve, the shares become more valuable. If those relations deteriorate, so will the share-price. Armed with that information, I'd suggest that you read the newspaper.
The State Department announced this afternoon that Cuba has been removed from its list of states sponsoring terrorism. It's expected that this will pave the way for the opening of embassies in Havana and Washington - an event that some anticipate may occur as early as next week.