Dude Who's Who said nothing that conjuctures racism.
It is discriminatin not knowing that fishmen are fast on dry land?
Then he asked someting to Jinbei because it has to do with slavery and fishmen was once slaved. What is the matter of getting to know the history? This is basically Oda saying Jinbei would hate Robin for trying to understand Void Century.
Who's Who is so out of racism that he didn't even understand why Jinbei got mad out of nowhere.
Just like current woke people(white) getting mad for nothing.