We can agree to disagree on this one, but ultimately, my view is that foreign policy is about the calibration of multiple priorities. For human rights to be the only priority in the relationship with a country like Iran, or any other for that matter, is not optimal.
As small a country as Canada is, as limited as its impact on the world scene is, it can, along with allies.... The best impact in terms of improving, promoting, and encouraging political reforms on democracy, human rights, and other fronts will come when engagement on human rights comes with other aspects, whether it's trade, whether it's diplomatic relations, and so on.
I don't see any proof that engaging only on the basis of human rights and therefore, not engaging...that making decisions only on the basis of human rights can lead to optimal outcomes from our perspective.
The other point I would add is on the plain inconsistency of that. Canada has relations with Saudi Arabia, and I think I'm safe to say that human rights in Saudi Arabia are worse than in Iran, or certainly not better. Are human rights raised in our issues with Saudi Arabia? Of course they are, but we have other interests too: business, strategic, consular, educational, and so on.
From my perspective the argument that we shouldn't engage with Iran solely on the basis of human rights is widely inconsistent.