Considering pregnancy can result in death (at a higher rate than kidney donation as noted elsewhere in the thread) as well as countless other long term conditions your 9 month limit doesn’t really make sense. But let’s say you could loan out a kidney for a few months, would you really find it acceptable for the state to forcibly seize your kidney to keep someone else alive?

Persuasion isn’t that important when the vast majority of the public already agrees with you.