Ask a criminal "Did you murder this guy?"
The guy: Ofc not.
I did not choose to comment on the fact if Keznit is racist or not. But what you are doing is normalizing ignorance and its not cool.
Cultural bias does exist but it is not an excuse for doing something stupid especially when you are a paid professional.
Imagine getting a job in Japan and creating a ruckus in public.
Or travelling to India and just casually ordering beef in a restaurant in a north Indian state.
An Indian casually using the N-word in a western country for black men cause that is what our history books refer to them as.
All of these things stems from cultural bias but are they cool? no. You might think this is cultural bias and you might not know any better but it is extremely uncomfortable/offensive to the people involved.
Know who you are working with. Keznit competes/plays/scrims with Brazillian players. He has lived in Brazil He should know better. He should know what words can be offensive for others. If he does not, that is just ignorance and once again, it is not a trait you should defend him for. I agree with the fact that you should not take someone's career away for such accusations but a paid professional should try to fit better with other cultures if they are interacting with it.