it's just an assumption from Elon, even though it's true that Mr. Szabo is Satoshi, he has to prove it himself to be valid.
btw. I really like Elon's way of joking, even though it's getting less and less funny

The fact that Elon Musk and many others believe that Nick Szabo is Satoshi, makes my belief stronger that Nick Szabo is NOT Satoshi. Believe me, Satoshi took those extra steps to confuse the cypherpunks, the Bitcoin community, and the general public.