Wikipedia says his great-grandfather’s name was also Elon. Compelling as the other theory is, this seems much more plausible as the reason for his name.
> Their first child, Elon Reeve Musk, was born in 1971, named after Maye's grandfather J. Elon Haldeman, with the name Reeve after her maternal grandmother's maiden name.
> Their first child, Elon Reeve Musk, was born in 1971, named after Maye's grandfather J. Elon Haldeman, with the name Reeve after her maternal grandmother's maiden name.
https://en.m.wikipedia.org/wiki/Musk_family