Especially if they're using a pad to protect the seat from any accidental leakage.
I've changed 4 diapers on airplanes. 1) In the lavatory. On the toilet because the tiny little lav didn't have a changing table. 2) On the spare seat (with a pad) beside me. 3) On the only flat covered surface the stewardess could find. Her bench that she and her co-workers used. I was very polite and used three extra wipes to clean the seat. 4) Because someone objected to it in the spare seat beside me, someone else complained that I couldn't use the stewardess' bench/seat (smaller plane, seat, not a bench that time), and two people were in both the lavs and he was screaming bloody murder, I changed his poopy diaper on the floor in the aisle. I wrapped it up in two bags and the stewardess disposed as if toxic waste.
I was applauded that time because a) I got the screaming baby to stop crying, and b) I let my wife continue to nap while I did it.
See, us guys can change them too. I've taken many a resturaunt manager to task for not having changing tables in the restrooms for men. I took the management at RDU to task for not having them at RDU the first time we flew with our oldest son.
Paul