That's not the issue. Continuing to have AIDS after you get it is not voluntary. Continuing to smoke is. That's why AIDS is covered by the ADA, but smoking isn't.
This is stupid.
I agree, but this employer has the right to be stupid.
Cancer related complications are probably also covered by the ADA, I would imagine.
Anal sex with men is the voluntary activity that may lead to AIDS. Smoking is the voluntary activity that may lead to cancer. Another cause of AIDS is sharing hyperdermic needles.
As such, can I fire all my diabetics?