Yes, very potentially. That wasn't before the MPAO case, but there are other cases before the Supreme Court of Canada such as the B.C. Health Services case. It had to do with certain workplace conditions that the employer unilaterally imposed by statute of the B.C. government, and then the union was deprived of the opportunity to negotiate. That was found to be in violation of the charter, and I think these terms could very well be found in violation as well.
On April 19th, 2016. See this statement in context.