I dont agree that anyone can be oppressed by speech at all. Even in your example of "kill the nigger", it would only be real oppression if it actually progresses from words to something more, such as physical violence or immediate threat of it. Otherwise it is merely a verbal exchange of ideas, however despicable. Being insulted is not oppression.
Also, your example is completely unrealistic. There is no situation in real life where whenever you speak up, you hear calls to be killed. Not in any developed nation anyway. You may hear lots of such calls if a black person speaks on a KKK rally, lol, but thats about it. Not in mainstream discourse. So minorities are not really silenced by hate speech at all. They may be bothered by it sometimes, but not silenced, not unless they want to be silent and go out of their way to be quiet. To silence someone, you need something more than speech, you need physical violence, or its imminent threat. And that is not something that happens in modern democracies.
I really dont like how you are trying to frame this advocacy of hate speech laws as actually helping the free exchange of ideas. It is the polar opposite of what hate speech laws and censorship are for, so it is dishonest and absurd. At least have the courage to admit that you are afraid of the potential impact of some ideas and so you simply want to give up freedom for security and silence the opponents. Stop pretending you are doing it for freedom of expression in some strange roundabout way, because you are not. Quite a few years ago I used to support some limited form of hate speech laws, but I never dared to pretend that it was anything else than an attempt to social engineer potentially dangerous ideas out of public consciousness and as such inherently anti-free speech and limiting. That is true no matter if you agree with such laws or not.
War is peace. Freedom is slavery. Ignorance is strength. Lack of hate speech bans is oppressive to political discourse. Yeah, right..