How is that relevant? People are concerned about bad things that might happen to them but haven't happened to them yet. Just because it hasn't happened to them specifically doesn't mean their concerns are invalid.
Because the frequency of an occurrence is valuable data relating to its likelihood, just like knowing whether your house is in a floodplain is valuable data in making a decision as to whether you should worry about your house flooding.
I mean, how many times has this happened to anyone, let alone the individual in question?
If they are using those terms in a way that is trying to stir up trouble, it makes sense to report them. If they did it without any intent to cause trouble, there wouldn't be an issue.
I don't call Japanese customers Japs even though that used to be a valid English term because it is now widely considered offensive. These are terms that some groups find offensive and more may find offensive in the future. It makes sense to stay ahead of the game and not cause offense if it costs me nothing to do it, and it makes sense for Google to help people who are trying not to offend people do so easily.
I mean, how many times has this happened to anyone, let alone the individual in question?