Ask HN: Is Elon Musk an expert in every field he manages?

Passionate comments on a LinkedIn post, following Elon Musk's tweet on management need for expertise in the field to be "supervised" https://www.linkedin.com/posts/kate-hobler_i-call-bullshit-is-elon-a-rocket-scientist-activity-6929470583139119106-JRrQ

Where does the HN community stand on this? I'm for the LinkedIn OP, but maybe it's because I'm too old, having been involved in too many industries, with a PhD in one domain (Thermodynamics) and a MS in another (CompSci), but still w/out having had the ability to master all areas which I had to manage in my professional career. I still don't understand the understanding process...