Even if he’s known to be mentally ill, his ideas can still stand. Take Ted Kaczynski for example. His actions were inexcusable but his ideas and writings on technology and its relationship to society have value.
PS: I'm not going to say what's true or false about any of Kanye's claims here, but who the hell knows what goes on in the highest levels of Hollywood? This is a circle of people who felt zero shame publicly disparaging critics of Roman Polanski. And apparently the Harvey Weinstein stuff was common knowledge in Hollywood crowds for decades. If you think Kanye has little credibility, well, think about how Hollywood's credibility ought to be perceived.