How about Duncan's seatmates on his three flights (ROB-BRU, BRU-IAD, IAD-DFW)? This experiment has already been performed, ethical or not. I haven't heard that any of those seatmates have got Ebola. And, based on what we know now, that is the expected outcome (unless one of them joined the Mile High Club with him).
Then there are the people Duncan interacted with between arriving in Dallas and becoming ill. Have any of them got Ebola?
And, finally, there are the people Duncan was staying with when he did become ill, the crew of the ambulance Youngor Jallah summoned, the guys power-washing his vomit, etc. Have any of them got Ebola?
It seems Nina Pham got Ebola exactly the same way her patient got it: by slipping up while caring for a maximally ill, maximally infectious patient.
I would not want to sit next to a Ebola infected person, symptoms or no symptoms. Viruses typically do not live long so if your clothing touched an Ebola infected person, chances are the virus will die before that part of clothing enters your nose, mouth, lings etc. But the risk is always there.
Also remember, our bodies have remarkable resistance to viruses and bacteria which enter our bodies every day we are out and about. The FOX news TV station inspected all the items in studio, and they found germs & viruses present everywhere. Every gadget, every door knob, every seat, every keyboard, every phone, etc had those organisms. Yet no one got sick. What is bad about Ebola is that most of us have no anti-bodies developed to fight Ebola.