I'm opposed to putting complex people in simple boxes and then making life-changing or life-ending decisions about them based on those classifications. I think that everyone capable of it should sign up for organ donation, but I can still respect that there might be somewhat valid reasons why a person wouldn't want to. Consider, for example, a man who has sex with men, who knows he'd be rejected on that basis, and who doesn't want to come out of the closet to the government. Is it fair to deny him access to organ donations?