To the creator:
To whom your speak to? Aren't you the one who brought this or just read it somewhere?
That means the creator can't sign with the 'r' key, similar to the 1LZtnC7Ck37V9uLGGXFmaVkeaLyzFLvf6W case.
This means the creator can't sign from any of the addresses. Only from the one whose public key is equal with the sum of the addresses' public keys. Just think this reasonably; if a malicious guy wanted to prove Craig Wright is Satoshi, why not just give you a signed message from the - 1C7X4UWpSa4GteWHaRBm49fMCC2SNvJQF - which supposedly a Satoshi's address instead?
It'll lure more victims to believe that without writing some bullshit about the second letter of seven addresses.