Like management, engineering is a discipline of means divorced from ends. There are certain vital skills that are shared amongst engineers regardless of their particular domain, and those are the skills most important for an engineering manager to have.

A computer engineer without those skills is merely an amateur physicist. A software engineer without those skills is merely a programmer. Ask a quant with no engineering background to put their ad-hoc scripts into production one day and let's see how that goes.

Musk might know some science, but that doesn't make him an engineer.