He's in the middle of a culture clash between (traditionally union-friendly) automotive industry and (traditionally union-hostile) Silicon Valley startup, and he appears to be tossing his lot with the SV startup ecosystem.

That has rubbed a lot of people the wrong way.

(Possibly more importantly: he's also fallen prey, it seems, to the traditional SV startup ecosystem behavior of overselling capabilities in the Tesla cars, which may be contributing to avoidable deaths as people assume the low-tier driver assist the cars actually have is real self-driving functionality. I'm not sure why this bug hasn't propagated to SpaceX; perhaps he's populated the company with enough rocketeers to know that it's very much a "Screw up and people die" industry, and he's hands-off enough to let them succeed).