The requirement of the act is that there be full consultation with each of the provinces, not that they each agree.
If the act is going to be invoked and directed to only one jurisdiction, one province, then the province would have to agree to that before it could be invoked. However, in this instance, I have no quarrel with the ability of the government, having done consultations with all of the provinces, to move ahead. Indeed, the province primarily affected supported the invocation of the act.