there’s no way anyone needs a permit to sing songs in a church

Sorry. In this case you're wrong.

This wasn't a regular service, with the regular church patrons, and the regular hymn book. This was a special musical concert, from a guy on a musical tour of Canada.

At this point the church is no longer a church but a rented hall for the purpose of holding a musical concert.

In Montreal, you need a permit for that AND the city recommends you submit your application 90 days in advance of the concert date - which they did not do.