Caribbeans are descendants of slaves, it's correct for them to call themselves black. But people from african countries that know exactly where they came from have no need to say that they're "Black" when they have their own national and tribal identities.
But those carribean Nations by and large regained independence far before they arrived to Canada. Nah they don't identify with oppression or pejorative monikers at all. At least I never saw a St. Vincent kid unironcally link themselves to oppression as part of their identification process.
So if "black" is to mean purely those without an ethnic origin outside the one forcefully given to them, then they would absolutely be excluded to. Their fierce identification is present in the fact that they refuse to call themselves African Canadian but rather Carribean Canadian. They know full well who they are and where they'll return to.
With that in mind, blackness should by and large be given to Americans and nothing more if we are indeed ridding ourselves of racial connotations. But I never once saw black outside some flimsy physical description surrounding specific regions. Which is why I can't see it as some threat to ethnic identity. It's kind of just some silly verbiage.