I'm commenting directly on the letter... hard to know how I could be much more "on topic" than that!

Is this the topic: "But let a white cop shoot a black criminal, and all hell is to pay." OK, is the letter writer calling Mr. Castile the schoolworker a "black criminal" because he has multiple tickets for speeding and driving without insurance? I think that is a purposeful mischaracterization of someone who seems like a decent guy.

Or this, "One thing is sure, however: White people aren’t going to go around shooting blacks because of it." That seems like a naive statement given the history of violence against blacks. One can hope, but "sure"? I'm not sure. 

Are the attacks racially motivated? Of course.