Astarion is a complicated character as there are moments where he has no reaction even to things you think he may disapprove of. For example, he disapproves helping the Tieflings but is neutral if you save the Tiefling child at the Druid Grove at least during my gameplay. He approves of selfish acts which would go in part with him being a spoiled, rich noble. He also approves if you allow the Tiefling to kill Sazza, the goblin. There are other examples as well but this is why I think Astarion is Chaotic Neutral. His freedom comes first, the lines between good and evil come second to him.
