Not sure. Not enough.

Because it is true that "Not your keys, not your bitcoins" but private keys can be stolen and we can not be sure that the person signs a message from Satoshi Nakamoto's private key is actually Satoshi Nakamoto or hackers.

To prove it is Satoshi Nakamoto, there are more things to be provided, signing a message from PGP key, then coding style and more.

satoshin@gmx.com is compromised