“To which Cuban law do you refer? Not that it matters. But only Cuber gets to define Cuban law, and an authoritative citation would be an interesting conversation piece.”
Most would actually consider that the Cuban takes priority as that runs through his father, not his mother. It’s been given earlier up the thread. Son of a Cuban national has automatic Cuban citizenship.
That's up to Cuber, not American legal "scholars".
A Cuban is whoever Cuba says he is. And it's completely orthogonal to American law. Anything else would be a cession of sovereignty.
If Cuba were to make JCB a citizen, you could just go down to the consulate (in Canada, maybe?) and collect your passport. It would be up to you to accept or reject the "honor".