I agree with you on most aspects of this issue, but I think you are carrying your argument too far here.
Sometimes good can come from evil. That doesn't make the evil any less evil, but recognizing the fact doesn't mean one is accepting the evil.
The classic example for Christians is the murder of Christ. He was innocent and undeserving of death, so his murder was intrinsically evil. Yet as a result of this evil act we believe all humanity was offered the opportunity to be saved.
Slavery is the ultimate human evil. It reduces human beings, made in the image of God, to merchandise, thereby insulting God himself.
It is a lifelong kidnapping and rests on a basis of assault, torture and rape.
But even from such extreme evil some good can come.
Apologies for the multiple multiple posts.
FR is being very weird today.