The average Mzungu is filled with prejudices about tropical diseases. For example when I casually mentioned to my fellow graduate students that I had suffered malaria several times, recovered and moved on, the ones sitting closest to me moved a minute centimeter and I began noticing serious isolation. My then girlfriend lifted the lid on it when she insisted on CDs "to protect [her] from Malaria".
In Europe it is routine to discriminate against the blood donations of blacks and other immigrants on unfounded fears of the blood containing "unknown viruses". The ban extends to their own caucasian people who have spent some time in Africa.
So it is not out of the ordinary to see Eric Duncan as a "potential permanent threat". While the two white medics will forever be heroes, Duncan would have lived the rest of his life discriminated and shunned. For the record and in all fairness, even survivors of ebola in Africa face untold stigma.
Incidentally how far has the HIV medicine cure come? Was the doc stopped?