If you had seen him pointing a gun which to your eye looked real, would you really think "aww bless look at the little boy playing with his toy gun"? Probably not. I also wouldn't think, "shoot the little scumbag". There is a long way between those two positions. Where someone is on that continuum is what is deadly.
The statistics seem to bear out that there is racism in the investigation of crime, stopping people, laws around drugs, Police reactions, reporting of crimes and reporting the Police reaction to crime. I know people hate statistics but what they show is a trend, rather than absolutes. If every single Police Officer is just slightly more likely to shoot a black suspect dead than a white one, there will be more dead black teenagers. Each case can be argued but together, they look damning.
Just slightly quicker on the trigger, just slightly more shoots fired, just slightly more likely to mistake the age of a suspect, just slightly more likely to think a black kid has a gun than a white kid. It isn't as easy as saying that this Police Officer isn't a racist or is. It is impossible to be raised in a white-dominated, Western, Christian democracy as a white person without having some vestige of racism, privilege, power, fear and all the other taints that history has left us.
If you are white and haven't looked at your own privilege and racism, can I suggest you do. implicit.harvard.edu/implicit/selectatest.html