This is not even true mercy. As Pope Benedict XVI wrote, God's mercy for grave sinners is seen when He grants the grace to repent and the strength to atone for their sins.
When you presumptuously presume to reconcile the unrepentant to God, you not only offend God, but you also endanger the soul of the unrepentant sinner. He no longer sees a need to turn from his evil ways, since he fools himself into thinking his many offenses are OK with God.
Exactly! And that's why footnote 351 in Amoris Laetitia is heresy.