> Control of Cuba could blockade New Orleans and thus the Mississippi.

For a few minutes, maybe, before whoever attempted to use control of Cuba for that purpose ceased to exist, along with all of the facilities they were using for that purpose.

The US military may fail at constructing stable democratic regimes on the far side of the globe, but obliterating someone doing that from Cuba wouldn't be a challenge.

> But keeping the island out of foreign hands is a legitimate geopolitical priority for D.C.

Its a foreign country. Unless the US invades and annexes it, whatever hands its in are going to continue to be foreign.