Nigger is not a word that get's thrown around very frequently by white people except by those who are actually racist or are intentionally use it to cause harm, or by black people themselves who are referring to someone of their own race in a negative light. So it would be out of character for Alec to use that word considering the general vocabulary and conditions of his upbringing. But if he did in fact use that word, it would more likely be seen as racist.
But he didn't. And you can bring up what if situations to try and manipulate "my logic" as you see it, but I prefer to base my reasoning on what actually happened.
So, let me know when you're not comparing involuntary swearing after being assaulted by a paparazzi to the physical act of manslaughter, because clearly hyperbole is something you're susceptible to and it's muddying your message. Cool?