Not only should people be able to wear what they want, when they want, I'll go further--I don't think immigrants should have to take public oaths at all and if I had to do so to keep my birthright citizenship, I'd be considering going stateless. My identity and my commitment to a country is not and should not be subject to testing or hoop-jumping, and that's a privilege I'd like to extend to my fellow Canadians, reagrdless of how they became Canadian.
I'd also add that I find submitting to a checklist of shared values to gain citizenship rights is pretty odious to begin with.
This kind of stuff is up there with accusing dual citizens of disloyalty on the list of paranoid things nationalists do to make themselves feel more comfortable knowing they're safe in their fortress.
*shrugs*