Choosing to wear a hijab is totally cool, as long as it's not because of a religion.
Religion uses coercion and indoctrination to control people.
It doesn't matter if it's state sanctioned or not: the social contract imposed by religion is violence. It doesn't matter if it's the government threatening jail time or your friends threatening social isolation. It's coercive.
And you can't distinguish between those who do it willingly and those who are forced: so a civil society can permit neither.