Both sides agreed that juries, whose deliberations are secret and cannot be reviewed, have the power to nullify laws by at times ignoring them.
Both sides AGREE that jurors have the power to nullify. The defeat of the amendment doesn't change that. The amendment would have allowed the defendant to ask for nullification by admitting that s/he did what they are charged with, but declaring that the law is wrong.
That is different from the debate at hand.