That seems to be the accepted fact. But I would add this --
Duncan was in Africa. He cared for a dying pregnant woman.
He then seems to have said, "Hmmmm. I've been exposed. I'm sure I'm going to die. I should quit my job, fly to America, and seek top medical help. Certainly I feel fine, there's no trace of any symptom, but I know I've received a death sentence."
And he was right about that. He got infected from his exposure. He thought he had a death sentence, and he did.
Why was he so vulnerable and caught it from the exposure he had, yet his family seems to have been less vulnerable and did not receive the immediate death sentence when they cared for him?
I know you get more contagious as time goes by, but he seems to have been darn sick before he finally got admitted to the hospital.
Duncan had to have started planning his trip at least three months before he was exposed, because that's how long it take to get a visa. Unless I'm misremembering, he also bought the ticket and quit his job before being exposed.
Arguably he should have remained in Africa because he knew he might become sick, but your theory just doesn't fit the timeline.
And he was right about that. He got infected from his exposure. He thought he had a death sentence, and he did.
You've not a clue what you are blathering about.
For a guy who knew he'd been exposed to Ebola, Duncan was mighty resistant to the idea of obtaining medical care in the Land of the Free. On his first visit to the ER, he didn't object when they sent him home with a worthless antibiotic prescription. He also objected when his stepdaughter called 911 to get him checked in a few days later. If his plan had been come to America to get treated for Ebola, he would have headed for Atlanta, not Dallas. Duh! And he would have had his story straight on how he got the disease.
Fact is, the family of Marthalene Williams, the infected pregnant woman Duncan handled, had insisted it wasn't Ebola, just pregnancy complications. We know this because of taxi driver Jiminez Grugbaye's account of the incident. Being somewhere on the right side of the bell curve, Grugbaye, upon reflection on what he had seen, fumigated his cab twice and went to a clinic to get checked. Sadly, Duncan was not so smart.
IOW, it's more than likely Duncan did not know he'd been exposed to Ebola. Marthalene Williams was the first case in the neighborhood. The popular perception of Ebola among Liberians is completely screwed up, as we saw last August, when a mob attacked a quarantine center and freed the patients. Liberians redefine the notion of "low information".