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.
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.