I wonder if it’s because 28 Days Later was shot on a handful of Canon XL-1’s, which was a breakthrough as they were one of the first prosumer cameras that could pull off a film like that.
Kind of a nod and a wink at the heritage of the story to shoot on consumer hardware.
To be fair, the entire issue of blackface and its sordid history is much more nasty and nuanced than this thread would suggest.
If you want to find out more, look into the racist nature of minstrel shows, and their role in maintaining hierarchy.