It is a little misunderstood, this subject. Double spend protection (partition resistance) is not the primary target of Bitcoin's design, it's consistency. The famous 51% attack relates to the fact that controlling half the hash power lets you rewrite recent blocks.

Bitcoin's main strength is its immutable history, which is the C in the CAP theorem.

What Satoshi actually said was that the EC cryptography solved the Byzantine Generals problem via unforgeable signatures on the messages delivered to the generals.

The heaviest chain wins rule, which was his invention, is the thing that people mean when they say "Nakamoto Consensus". It is what keeps the majority of miners on the same chain and thus preventing reorgs, and further reducing the viability of double spend attempts.