This is the difference, coach. Here is the answer to the Riddle of the Leon Spinx.
Whites look at an attack of this kind as an isolated incident committed by individuals who happen to be black
Reverse the roles
Blacks look at an attack of this kind as representative of institutional white racism inherent in all white people
I'll be honest, every white person I've ever known (including myself) has been unnerved when casually passing a young, black man.
To be even more honest, most of those white folks had nothing against black folks (some hated them to be sure), but they always have a slight fear that something might go down.
To be completely honest, if I was walking down a street by myself and saw a group of black men in the distance I'd probably about face and find another route. Could be the men are harmless friends, a study group at the local college, a church choir or a violent gang of thugs lookin for blood. Since I can't be sure until it's too late I don't take the chance.
No different than a lone black man seeing a group of white men coming towards him in the distance in the Mississippi or Alabama or Texas.....can't be sure, don't take the chance.
Is that racist behavior? Yes. Is it unjustified? No.