If a Black person calls their friend the n-word in a joking way it's seen as affectionate. If a white dude, especially one who is an asshole and not friends with the Black person, says the n-word, it's an insult. This is a similar situation. Especially since Donaldson is a white supremacist asshole with a history of stirring up shit with the White Sox and not friends with Anderson in any way that would make "Jackie" an affectionate jibe. The white supremacists know this but they will never say it out loud because the gaslighting is part of how they advance their "supremacy."