What these asshole border agents did will likely result in Canadian border agents giving American visitors the same treatment, with or without cause.
Sort of a tit for tat type situation I think. Canadians don't like being bullied, and their government usually sticks up for them in these types of situations I believe.
And as people here have rightfully noted, all of this trouble over a couple of Canadians who wanted to spend some of their money in a US mall, whereas truly malicious vermin are being allowed to overwelm the southern border states at will. It's insane, totally, absolutely, and outrageously insane.