Is it safe to travel/fly after a appendectomy?????!!!!!?

My sons father and grandmother planned a trip from where they live in Texas to Pennsylvania. Now they can always reschedule for another time but he misses him. But this morning he had to get his appendix taken out because it was about to rupture. So today is saturday and he had surgery. Would he be ok to fly that 4 hour flight next saturday? He's gonna be in the hospital for 3 nights then go home. I don't see why he couldn't I mean it's gonna be a a mini vacation for him. He wont be doing much of anything. I mean he's a tough guy and I think he would tough it out but is it safe????