How many black people were actually voting in Georgia in 1960, though?
It's still pretty relevant that the ones who were voted Republican while the Northern Black vote had abandoned the Party of Lincoln decades prior.
Not everywhere. There was a black Republican machine in Chester, Pennsylvania that was dominant in the city until the Obama years, e.g. (75% black Chester had three successive Republican mayors continuously from 1996 to 2012). Of course, blacks in Chester had switched to voting Democratic federally earlier, but I bet blacks in Chester voted for Nixon.