"Free" countries may also (as you point out) outlaw masks or face coverings on security grounds (facial recognition). I'm not saying I approve of all this, just that your point above about the government making decisions about dress isn't right. Though I don't trust Sarkozy's motives, I don't see anything fundamentally reprehensible about him expressing a view on this subject. If it means he will ram legislation through without debate, without seeking consensus, then I will find that extremely reprehensible.
But I am against the state doing so based on an interpretation by the state of what the (un)dress in question is a "sign" of.
To me personally, it is of little importance whether it is Sarkozy or anyone else advocating such a policy. Truth unfolds in time through a communal process.