Or maybe he thought all the Castro’s would be dead and gone and their government fallen. I could see a scenario where Castro was behind this. Because Russia was complicit, the US didn’t want to look weak by not responding in the face of an overt act of war.
A bunch of confusion and blaming civil rights gobbledegook was the perfect excuse for doing nothing in response to Cuba’s actions...which could have kicked off an even bigger war with Russia.
That’s just my personal theory.