Should organ donation upon death be opt-in or opt-out?
Opt in. The dead can't vote.
If it were opt out then wouldn't it unlawful search and seizure?
Well, you are dead, so one could argue that you don't have any rights at that point.
My estate has my rights.
I don't think you can assume someone's wishes. I think a person should have to explicitly opt in otherwise you might be going against their beliefs.