Satoshi may be the creator of future technologies and currencies, but he is not a prophet, so he will not be able to know the quantum computer creates. But Satoshi has created a new world when adventurers can find their treasure when deciphering Blockchains, which is the best thing for many people.
He can think that it is possible for the technology to decode Bitcoin hashes and find private keys using the public key if Bitcoin technology will not improve but Satoshi is well aware that before that thing happen, developers will do their best to prevent it. Bitcoin technology as we know is not stagnating. There are several updates and upgrades that happen to it and right now developers are also well aware of the possible threat this quantum computers to Bitcoin so they are already creating ways to improve Bitcoin security, that is for sure.