Did you not watch the Netflix documentary? The last episodes contained many non-obviously-sane conversations. Especially the one where he was talking to bankers at one of their vacation homes.
I’ve seen plenty of weird conversations in the workforce like leaders living in an alternate reality than direct reports to hawk their views, yet never felt motivated to call them mentally ill. I don’t judge how people feel they need to speak to relate to anybody, especially under the influence of alcohol as Kanye was in that segment.