It’s kind of a miracle Americans didn’t retain the servant in blackface when they adapted Sinterklaas into Santa Claus. Santa Claus was popularized around the same time as minstrel shows yet somehow that aspect was completely avoided.
We didn't retain his boat either, which is really too bad. Just imagine the America where we'd been conditioned for centuries and from coast to coast to expect navigable shipping canals wherever we live.
I’m gonna go with, “More racism, alas,” for $200, Alex. My guess is the advertising that made Santa Claus popular were not interested in 1) selling to Black people and 2) did not want their white customers afraid that a mythic black man would be coming into their house.