An extreme version of this is: What should the German health service do if someone says they are willing to donate a kidney as long as it doesn’t go to a Jew?
On the one hand, nobody is forced to donate a kidney and by forbidding this we’re making things worse for an innocent patient. On the other hand, it can be seen as the state sanctioning this kind of discrimination.
You’re kind of talking about different things. Copyright should of course be abolished along with all private property. I don’t rule out compensation to your estate for organs harvested after death and there should definitely be a public bounty/reward system to encourage the living to donate.
You shouldn’t be able to opt out, or at least it should be very difficult to do so, because when you are dead what you have a say in that affects the living should be very limited, because those organs won’t matter to you anymore, and because those organs might matter very much to living people. Whether you trust society or not doesn’t matter anymore when you are dead.