You must be white (to be surprised by this reaction). White Americans engage in all kinds of mental gymnastics so as to not have to confront the sheer brutality and inhumanity of all kinds of American racism. They don’t want to be associated with such filth (understandably) and are quick to distance themselves.
However, they do so without even taking the time to realize…the behavior of all white people is not really the point here. (And that is deeply offensive if we’re talking the pointless murder of a person of color, as obviously that SHOULD BE the point…not what all white people are doing.)
But the bigger issue (I think) is that large populations of white Americans are terrified of the sins of American racism being placed at their feet. Most do not want to take any responsibility for any of it (and who can blame them…the situation is such a clusterfuck, and the responsibility does not belong to all white people, equally. That is an utterly ridiculous idea, white people are understandably going to push against it.
But certainly it belongs to some. It belongs to some way more than others. That has to be acknowledged…especially when you ARE a white person running around killing black people on whims.