The Supreme Court has been there, done that regarding face coverings. If you are allowed to wear a face covering at a citizenship ceremnony, what would possibly be the point of ethnic screening for the same thing prior to entry? You could not get that issue in front of a JP, never mind the Supremes..
https://www.theglobeandmail.com/news/politics/liberals-drop-controversial-supreme-court-of-canada-niqab-appeal/article27280846/