Let's flashback even further to about 1966. Compare the apathy and arrogance of today's celebrities with this photo of Stewart, a brigadier general in the Air Force Reserve, at about age 58, looking like God in a flight suit, walking away from a B-52F, after a mission over North Vietnam.
I have no idea how many flights Stewart made over Nam--but even if it was just one for this photo-op, think of what he had to go through: the 5000 mile flight from Los Angeles to at least Guam, where most of the B-52s flew out of during the Vietnam war, the risk of getting shot out of the sky by crack North Vietnamese anti-aircraft gunners and killed or captured, plus the timeout from his career, when by the 1960s, he was earning at a minimum, in the very high six-figures per movie. I'm sure that when the call came, if Stewart or his handlers quietly said, "err, no thanks", the Air Force wouldn't have pressed the issue. But, just as he did in WWII, Stewart served his country.
(Les is picking his jaw off the floor right now. He'll be back after the reattachment procedure is completed.)