If efficiency was what he was after, he could have just said, "hey you look bored, would you feel more engaged if you were working on a migration to react?" Failing that, he could have clarified what he was going for after noticing the author missed it. Either way, it seems like the communication failures are more on the manager, for not having the awareness to appropriately direct the conversation and understand his needs, rather than the author, for failing to appropriate guess what the manager was obscuring.
This remains true even if allistics are generally better at such guessing.
If he's happy with the results of his efforts, then he doesn't need to take any advice. If he's not, then perhaps he will be interested in suggestions that he can implement, rather than "make your manager better".
This remains true even if allistics are generally better at such guessing.