Moving goalposts, I see. But this is a tricky situation, because while I fully support people having the right to end their life if they choose, they need to be of sound mind when making that decision. Someone who is severely depressed is not exactly in a mental state where they can make that decision - something I'm intimately familiar with personally.
I'm not assuming they're the same thing, hence why I reference them separately. Organ donation is one aspect, donating to science is a separate aspect. My body might not be super useful in a medical school if it's missing a bunch of organs, at which point something like a body farm might be a more effective use for it.
If I make arrangements for both (I've already done the former, officially registered as an organ donor), my family cannot override that decision upon my death.