Everything changed from 1960 to 1961? Or even from 1950 to 1961? Not likely.
Actually Hawaiian census categories came into line with US categories after statehood, so the categories in the 1960 census were different from earlier ones.
But if you were used to listing people as "Filipino" or "Portuguese" or "Puerto Rican" you wouldn't find "African" much of a stretch, all the more so if you didn't actually see that many "Negroes" around.
In some of the tables for the 1950 Hawaiian census African-Americans were listed with "Other Races" and were only a miniscule part of the population.
In other words, is there any evidence for what you say or are you offering an opinion?
What isn't an opinion where this sort of thing is concerned? You can find the categories used in the 1950 Hawaiian census online, at census.gov, for example.
See my point one, though. Birth certificates intended for the family aren't always as category-bound as those intended for the authorities.
If you were filling things like this out for the family you probably weren't obsessed with Mainland ideas of racial categories.
Again do you have any evidence anyone at all listed their race as "African"? I understand what you're offering as opinion, but I'm more interested in evidence.
Oh yes you would. There are plenty of black (or negro if you will ) people in the south Pacific. They don't and never have called them Africans, or identified them as having at one time in their ancestral past as having come from africa. That's because they aren't from Africa.