What reason would they have for telling the truth? A spy agency's official communications are always meant to elicit some response, it is never simply to disclose some information, since their default mode is to hoard information.

In this case, their motive is obviously to create an image of Cuba as a devious enemy of the United States who is willing to hurt low level officers in chronic ways, a dishonorable enemy.

This probably comes in the context of generally improving relationships with Cuba on almost the entire American continent, while the USA is still maintaining its illegal embargoes.

Now, is it possible that they chose to use a true story to advance this narrative? Yes, it is, absolutely. But if they want to spread this message and don't have a true story they are willing to share, nothing would stop them from sharing a false one instead.