In war there is no right or wrong, look at the Second World War if you reasoned so every single German soldier had to be punished. In war the one who is punished is the superior in this case is the king of demons, Mael is the same speech no one accuses him of the massacres carried out against...
The stories of the characters always have in common the same thing, Meliodas who looks at them and smiles. With that smile Meliodas gathered all the members