I look first at Law No. 23/2002 on Protection of Children and I find in Article 13 of that Law that a child, while under the care of parents,guardians, or any other parties responsible for the custody,is entitled to protection from any form of discrimination. If we consider the above action as a discrimination, judging from the text of the Law, I doubt that the school can be blamed, since the text seems to be intended to protect children from discrimination by their own parents or guardians. A school might be considered as a guardian of a child during the school time, but if the child never enrolled in the first place, there would be no legal obligation to protect the child from any discrimination. And based on that notion, I can see why the school chose to instead cancel the admission rather than accept the kid, if the kid is already in the school, the school will be obliged to protect her from any kind of discrimination.
So what would be the answer to this problem? Let's take a look at the reasoning used by the school to cancel the admission, i.e., they say that other parents disagree having a child with a potential HIV in the school. If this is true and these parents are the majority faction in the school, I can see why the school ended up with their decision. I bet they know that in the modern interconnected world like we are having now, this case will cause public controversies, there will be uproar, and to certain extent their name will be tainted. But, as long as their legal risks are low and most parents whose child go to their school support such policy, their benefits are still higher and there will be less incentives to change such policy.
Should we change the law then? Should we impose liability to the school for cancelling the admission? Should we force them to accept a child whatever his/her sickness is and whatever the probability of that sickness in infecting other kids is? I admit, these are very hard questions, and before we can answer those questions, we should analyze first the economics of preventing risk of infectious diseases. The State of Illinois can be a good example where it requires all international students to have immunization from certain diseases. Failure to do so within a certain time frame will cause the students to be rejected from registering for the remaining quarters in an academic year. Can we call this as a discrimination to immigrants or visitors? Might be, but voters love a state that seems to protect their citizens interest and the state can always say that it has the obligation to protect its citizens from any unwanted casualties.
This is precisely the problem faced by the above school. On one hand, the risks of accepting a kid with HIV positive might be very small to the other kids enrolled in such school, after all, HIV is not a disease that can be easily transmitted to other person. But on the other hand, even though the risks are small, the majority have different perception, which, I suspect, is caused by availability heuristic, i.e., since HIV is such a famous disease with significant adverse effect to a person's health, people tend to think that the risks of having such sickness is also high and therefore they reject any possibility of having a kid with HIV positive around their kids.
If my prediction is correct, imposing liability to the school will make no sense. You can't expect them to solve the problem that is out of their control (you can't control the preference of all the people in this world and it would be even harder if these people are already becoming your stakeholders), and it is likely that even when the kid is finally admitted, she will receive more discrimination from other kids and their respective parents (because we know that even when the kid is not admitted yet, some parents have already voiced their concerns and rejections). It's a bad game for the poor kid. Of course, this should not be the end of the world for the kid.
Other schools might actually take this opportunity as a marketing tool. But to achieve that, they must state their policy from the beginning. As an example, they should say that their school is opened to any kids with HIV positive and that they will provide a safe environment for everyone when they open their school registration. Stating this from the beginning will have the effect of screening parents that might not agree to have their kids sharing a class room with a positive HIV kid and therefore, we can expect less rejection from other parents. Only parents who support such idea who will send their kids to the school and this will allow the creation of a better environment for the HIV positive kid.
Borrowing the term from one of my Professors, Lior Strahilevitz, we can call this strategy as an exclusionary vibe. You effectively screen people who disagree with your policy and discourage them from getting into your community without having to say that you reject them. It's a double edge sword, it can be used to discriminate people, but it can also be used positively, as in creating a healthier environment for kids development. Furthermore, can this be a good business? I would think so, there are still many people who buy the idea that having a non-discriminatory school is good for the education of their children. And when these schools can attract many students, other schools will soon follow.
To close this post, in dealing with hard cases like this, sometimes, imposing liability would only increase the costs for each parties involved and might not be beneficial for the kids. Using strategy to raise public awareness is good, but I would suggest not to continue with a legal fight unless we can ensure that the problem lies within the school itself and not the parents. Because if the other parents are the problem, punishing the school will only add more fire to these parents, and the end result might be backfired. Remember, you can't control people preferences, it would be more effective to screen these people out and build a different business. If it is profitable, and my guess is: it is, the problem can be solved quicker than we thought.