I'm pretty neutral on Musk but he has an established track record of saying stupid shit on Twitter and ruining others' days/lives. Market manipulation, libel, trolling, etc. I guess I don't trust that a man with that kind of track record would be a positive influence on the social media hellscape we already have.

This is acknowledging that he also shares awesome stuff, like technical SpaceX details, and that he often engages with people in a real cool way.