This was a joke about how blood donors wouldn’t take blood from Gay/Lesbians because the media at the time that gay/lesbian people have a higher risk/have more instances of getting HIV/AIDS than straight people. This has since been debunked but some donors still don’t allow Gay/Lesbian people to donate blood for this reason.
Yeah, HIV/AIDS in lgbtq+ communities got more attention purely because it was in LGBTQ+ communities and at the time and most families were against the LGBTQ+ and also the LGBTQ+ was controversial at the time.