What is the ruling on a Muslim buying, carrying, or pouring alcohol for his non-Muslim parents, especially if they are opposed to his Islam?

It is not permissible for a son to assist his parents in drinking alcohol in any way, nor is it permissible for him to sit with them while they are drinking it. He must invite them to Islam, seeking Allah's help and being good to them, and supplicating persistently. If the young man is unable to uphold his religion in his country, then emigration becomes obligatory for him.