Have you ever actually seen this?
Or, failing that, have you ever read the Alex Haley book "Roots"? or seen the television series based upon? There's an entire scene of protagonist Kunta Kente being whipped savagely as the slave master repeatedly asks "what's your name boy" to dehumanize him and strip him of his birthright and birth-given identity, changing his African name to a white, Anglo-Christian name.
I can't think of a better example than that of how that word came to be weaponized against an entire group of people to the point we have come to now.
"Boy" to black people (hi there, black person here) has a LOT of history of being blatant, unambiguous and pretty darn direct.
Although...
I suppose it's easier if one hasn't lived that life though to rest their laurels on what they "imagine" versus what people like me continually have to point out actually happens because we're the ones living through it.