But I think with Musk the answer is that people respond extra harshly to perceive hypocrisy. The Kochs are almost cartoon corporate arch-villains and the Saudis are brutal theocrats. No one has any illusions that they are good people trying to help the world. Musk, however, has been presented as a Good Guy by both himself and a largely fawning press, set up as some kind of technology messiah. I think people therefore react strongly when, of course, this proves not to be true and that he's just another businessman, albeit one who does genuinely seem to want to help people.
They get very little tech-circle-specific criticism, because that's not where they operate (and because they have little in the way of tech-specific cult of personality, to provoke domain specific response expressing the general criticism.)
But they get a lot of criticism from non-tech-specific groups that themselves substantially overlap tech circles.