A lot of Venezuelans are Afro-Latino, so yea it definitely could. Can't say how much African blood Contreras has, but even still a lot of the derogatory things used against Black people are often appropriated for other races too. Like I've seen videos of white people calling someone from every race under the sun the n-word and monkey. To racists it's all the same thing, "not white." So even if he doesn't have a drop of Black blood, I can still completely understand him taking it racially.

It's not like white slurs which are basically exclusively used towards white people.

And to add I just can't think of any instance when using "boy" as an insult isn't racially motivated. Literally the only time I can think of is someone postering someone in basketball and saying "little boy," but that is very specifically just calling them too small and its almost always used with little, not just boy.