I'm surprised article claims that photography and film are no longer 'racist'. Most of my photos are underexposing dark complexions. It might be to do with limited dynamic range though, but still exists.
Is it dark complexions or everything dark. It might be that it is only when it is a a face you notice the lack of details.
“Racist” is being used metaphorically. The choice of film chemistry to use will affect what sort of faces are captured well, and what sort of faces are captured poorly.
Not only the chemistry or the sensor, but also the exposure. If you want to see details in dark areas you need more light.