If there were a species whose average adult intelligence was that of a human three-year old, then yes you'd be limited in what you could teach them. But as for what AIs can teach humans, you have to assume we are using competent smart adults. My claim is just what AIs can teach competent smart adults is many many orders of magnitude more than what humans can teach competent smart cockroaches. Thus Hofstadter's analogy is not a good one.