You can probably make a convincing case for it in the realm of dating /having sex, but there's more to life than that.
Should people with stds be denied life insurance because of it? Should they be denied jobs? Should they be discriminated against in the housing market? In the legal system ? In the medical system ?
There's too much Stigma associated with AIDS especially for involuntary disclosure to not cause pure chaos in this society. For some people, when they here HIV they think immoral, irresponsible , whore/freak, probably always sick, and on the fast track to death. No one will want to hire that person, insure that person, or live next to that person. And because African Americans comprise higher rates of new aids cases, such a law would wreak havoc on an already suffering community.
Terrible idea