None of them have carte blanche protection for freedom of expression as the Charter does.

E.g. Quebec law is applicable in this case, and while the law lists freedom of expression as a fundamental right

Every person is the possessor of the fundamental freedoms, including freedom of conscience, freedom of religion, freedom of opinion, freedom of expression, freedom of peaceful assembly and freedom of association.

the protection for that freedom only extends to discrimination.

That is, the law does't say you can say anything you want without consequence from an employer. It just says the employer can't impair that freedom by discriminating between people based on certain factors:

Every person has a right to full and equal recognition and exercise of his human rights and freedoms, without distinction, exclusion or preference based on race, colour, sex, gender identity or expression, pregnancy, sexual orientation, civil status, age except as provided by law, religion, political convictions, language, ethnic or national origin, social condition, a handicap or the use of any means to palliate a handicap.

Discrimination exists where such a distinction, exclusion or preference has the effect of nullifying or impairing such right.

So Air Canada can ban all employees from expressing support for terrorist activity, as long as it doesn't discriminate in the application of that policy.