Yeah I mean it's pretty obvious that WaPo political operatives just dug this unknown detail up in an attempt to smear Musk as an anti-Semite, because that's easier than actually trying to argue with his claims via fact and reason.
It's pretty clear from the movies that Magneto was a Holocaust survivor. I'm pretty confident that Musk knows this, and was clearly peeved that Soros had recently sold his T$LA holdings. The man's pettiness knows no bounds.