What benefit might be expected from deliberately misidentifying the source of the sound, especially given the probability that it could be correctly identified at any time?
Florida is often seen as a state that can go either way in a Presidential election. Cuban exiles are a tiny percentage of the electorate there but wield huge influence since they vote so to curry favor with these exiles some politicians use being hard on Cuba (whatever way one wishes to interpret that) as politically unrisky - those who are on the other side of the issue or neutral or ignorant of this are not one issue voters compared to the Cuban immigrants, this is supposedly changing slowly with the next generation of Cubans in Florida.
I suppose it could provide diplomatic leverave and stir up public fervor against Cuba, which might allow the US to launch an operation against the government in Cuba that the US seems to not tolerate very much.