If he is cleared for "normal living", and moving around the city without having to be close to emergency care there is absolutely no reason he can't fly in a pressurized commercial airliner.
That is usually a question for the doctor. However, I will let you know that 7 days after my brain surgery, I flew home coast to coast US so 47 days after his, he *should* be fine as far as time goes. He should have a follow up with the surgeon coming up so you can ask.
Hope he does well! Enjoy the trip.