Would you mind elaborating for someone who also does graphs a lot and tries to keep them colorblind friendly? What makes the grey easier to distinguish than (say) just white?
Here is a good resource I have used in the past for visualizations that I tried to make color blind accessible. (I have tritanomaly and I have worked with and designed some visualizations for folks that are red-green color blind.) https://colorbrewer2.org/#type=diverging&scheme=BrBG&n=3
I feel like this particular map would work better for a sequential color scheme than a diverging one. But either way there are several suggestions that will work. For a diverging color scheme, you just really want the middle color to be more neutral. Gray, beige, and white all work.