Maybe the hostility has something to do with people (like the OP) who promote the idea that the “Negro” race is genetically intellectually inferior. A bit odd not to feel hostile when old ideas like these are bubbling to the surface again.
Also….just to be a bit realistic here. White society as a whole did not support Civil Rights until a certain tipping point was reached. I read in one account that it was the murder of Goodman, Schwerner and Chaney, 3 freedom riders (of which 2 were white) that tipped public anger into decisive action. A segment of white society supported it, but certainly not many southern states, where black children face open hostility in newly desegregated schools.
There is also a certain…I’m not sure of the right word, maybe discordance in the fact that there are those who insist that Blacks need to be grateful to Whites who fought for their rights…and chide them for a lack of gratitude and humility, yet it was Whites who took those rights in the first place.