That was simply because, well, if you had reason to get an HIV test, you're obviously doing something that puts you at risk, so we're not going to take a chance on you and insure you. That was reality back in the 1990s.
I think a good piece of news is to show a piece of very faulty data that was out there. You probably heard the recent announcement in the last couple of months about the infamous “patient zero”, the Air Canada flight attendant who was basically blamed for the introduction of HIV to North America. It turns out that it was all based on faulty data and based on assumptions. On further review of that data, it turned out that it was completely wrong.