I think only you can know for sure.
My current boss is somewhat like this, only worse. He asks me to review and comment on things (in email, since he does spend a lot of time in meetings, on trips and in other ways out of his office), or sends open-ended or technical questions that can’t be answered in one-sentence answers or other simple ways. So I respond in kind, for one thing because he’s not in his office down the hall, and for another, to give him a timely response, but also to give the response the consideration that the question or review requires – and also to preserve a record of the response.
Then when he gets back to the office, or near it, he’ll send a follow-up email to “come see me” so we can talk about the email that I may have sent days earlier… and when I walk down the hall (and around the office), I find that he’s still unavailable. So I leave a message in his office for him that I tried to find him and didn’t, or I email again to elaborate on the answer that I’ve already given, in case there’s some open question (or in case I’ve learned more since the question was asked) ... and wait for him to get back to me.
When he finally gets back to his office, then he’s rushed, pressed for time, late for a dozen meetings… and he shows up at my office to demand an instant update on an email that may be, by now, a week or more old (and may have been covered with other emails following the same pattern).
So I end up giving rushed, incomplete oral synopses to questions that I took a lot of time and care to answer “just right” the first time… and he only absorbs a fraction of what I tell him (which was a rushed fraction of what I wrote him) ... and then he gets part of that wrong.
And he wonders why he has no time…