Your logic works only if you can safely assume that one did not have significantly more hash power than others. Rational speculation, but inconclusive as a proof.
until december 2009 hash power wasnt a big deal as difficulty was meaningless. and it wasnt until someone else made CG miner to utilise GPU power did the game really change. and satoshi was then behind the curb by then.
i remember in december he actually requested a halt on the hash arms race because he liked it that everyone was on an equal par by just cpu mining