If you agree with their premise that "some people might be made uncomfortable by the existing wording", surely removing it helps those people?

Is this the last remaining piece of racism in our society? No.

In some sense, it doesn't. But the point of these measures is to be anti-racist. To make the environment more welcoming to people of colour. Maybe the majority of people of colour don't care, but I am sure that some do.

In my own experiences, being actively welcoming provides a level of safety that silence will not, because the status quo is that it is not safe for me to be myself, even if I might plausibly be accepted among my specific peer group.

Overall, these are small changes (what github is doing notwithstanding), and the amount of time onlookers have spent whinging about them far exceeds the time spent making the changes.

No, this won't address the most pressing systematic abuses by minorities, but it does make one of the most lucrative careers less actively hostile to them.

Even though many (or even most) people probably aren't offended by terms like blacklist or master/slave, there's a non-zero number of people who are. Obviously changing terminology isn't going to end racism, but it will have a small positive impact on some people. Even if 99% of people don't care, they're not harmed as long as the new terminology is clear. IMO there's no semantic loss by going from "master/slave" to "primary/replica" or similar.