No freedom is absolute.  Nudity is prohibited because it is considered indecent.   Perhaps a similar argument can be made for covering one's face as a matter of course, at least by Canadian standards.

Additionally, you refer to the niqub as a religious item.  I understand that modesty is considered a virtue in Islam, but I don't think there is any religious requirement to wear a niqab.  It seems to be more cultural than religious.