> Has anybody more competent than Elon (which isn't a very high bar) survived contact with him in one of his firms?

Gwynne Shotwell.

Competent enough not only technically, but also to "handle" Musk to keep him away from her.

https://www.reddit.com/r/EnoughMuskSpam/comments/z2ofwk/i_wa...

I wonder if he ever asked her to bear his child.

https://www.vanityfair.com/news/story/elon-musk-reportedly-a...