Let’s not tar and feather Justinh just yet. At the risk of giving him too much credit, I am going to take this question seriously. I am assuming that he is viewing the spread of HIV with amoral logic and and a hypothetical point of view, rather than a mad-scientist Joseph Mengeli point of view.
Quarantines are designed to protect the greater population, and they operate on similar reasoning to the OP. If the human resevoir can be isolated, it prevents the virus from spreading outside that resevoir (assuming that, like AIDS, there is not another vector). What justinh seems to be suggesting is a “death quarantine” where the virus is isolated because the infected are killed and disposed of rather than merely sequested in a leper colony. If HIV was ebola, smallpox, or the swine flu, this might work. It’s one of the most morally repugnant scenarios I can think of, but it might work.
However, HIV is not any of these bugs. It is a retrovirus capable of lying dormant in the human body for years. It is undetectable by the currently available antibody tests until it “awakes” and provokes an immune response. Therefore, standard blood tests will never catch all those infected - only those who have already begun to produce antibodies to HIV. There will be a small but signifigant segment of people that will test negative and escape the HIV Extermination List (HELL) - yet develop the syndrome at a later date. From these few, the disease may spread again, especially if the general population grows lax in prophylactic measures due to an overconfidence in the completeness of HELL.
Now, what if some other method was used to test for the virus itself - such as a Southern Blot; or as the OP suggested, a magic bullet “anti-vaccine” was developed that killed all those infected with the virus. The Extermination Vaccine decreed by International Law (EVIL) would have to be administered to all 6 billion people on the planet. Since EVIL does not provide immunity to HIV, it would also have to be administered to all 6 billion people within a matter of months in order to prevent cross infection from those who have not yet been given EVIL to those who had already been given EVIL. This is a logistical impossibility, for if one small infected segment of the population slipped through the bureacratic cracks, AIDS would spread again, especially if the general population grew lax in prophylactic measures due to overconfidence in the infallibilty of EVIL.
So, death quarantines would not work on a global scale, but what about a smaller one? There is an interesting ethical question here, for these types of drastic measures are not without precedent during times of plague. In 1720, an act of parliament attempted to isolate Marseilles by levying the death penalty as punishment for any communication between the city and the rest of Provence. (http://www.beyond.fr/history/plague.html)
Now, Imagine you are a member of a small English colony sent to the New World. Small Pox has broken out, killed a quarter of the population, and infected another quarter in a matter of weeks. The colony does not have the resources to combat the disease, nor does it have the facilities for a quarantine. Banishment means certain death. Panic is breaking out as the population dwindles; what do you do?
On a side note, in Virtual Light, Willian Gibson imagines a clever take on an AIDS vaccine. The virus had produced many, many, variants through mutation and one was found to be both non-fatal and non-symptomatic. It was then injected into the population at large because it also provided immunity to the other strains. It looks like his idea has even more merit than he might have thought: http://www.nih.gov/news/pr/oct2001/nichd-31.htm