He thought Moore's law would keep up with the scalability demands...
Moore's law has never applied to bandwidth (so if Satoshi really thought that then clearly he wasn't a genius was he).
Or perhaps you think that because Satoshi could never be wrong then if he said that "Moore's Law" applies to bandwidth it actually does?
You can read his thoughts in the opening post, although they are
subject to different interpretations.
Bandwidth is just one factor in validation.
Satoshi had profound insight into systemic dynamics, and I wouldn't
hesitate to call him a genius. But I don't think he was omniscient.