A bad decision by the developers that doesn't inspire confidence that they won't have made similar bad choices elsewhere...
The history of civ shows the objection to this isn't about the characters skin colour and/or sex. It's just an incoherent casting when there's literally no reason to do this, even within the DEI worldview, as previous Civ's have had plenty of 'diversity'
I've played every Civ extensively from the first but i think this will be the first I'll leave for a year or two to wait for the expansions to come out and the price to drop.
Edit: i see they have decided to include Confucius and Niccolo Machiavelli which is a departure from previous games where all the leaders were.... well actually leaders of nations/ tribes etc at one point or another either formally as head of states or less formally like Gandhi.
But at least thoose two did hold high influential positions in goverment unlike Tubman.