I didn't take the time to delve in to other tweets, but if you know more about him, can you tell me whether, based on what you know of him, he is saying "black people are niggers"(0) or "I won't be shamed into not using a word"(1).

Based on just the tweet, it sounds like #1. If so, I can only repeat "I disapprove of what you say, but I will defend to the death your right to say it". And, furthermore, I don't think that, in itself, says he's racist.

No, it's the first one. He's a pretty big bigot and racist. He's also been diagnosed with a form of schizophrenia, so take that for what it's worth.

He often makes those kind of comments. But he's schizophrenic, so it's probably not entirely his own fault.