What is the ruling on one who styles the hair of a veiled woman who uncovers her head in front of non-mahram men?

If the woman who styles hair knows that the woman will uncover her head in front of non-mahram men, then it is not permissible for her to style her hair, as this falls under cooperation in sin and transgression, which is forbidden in His (the Almighty's) saying: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression. And fear Allah; indeed, Allah is severe in penalty."