When I say it’s possible, I don’t think that it’s the official CBP policy, but I have had enough interactions with power tripping cops to believe that it’s possible that the kid was disrespectful to the wrong guy. Customs agents have wide latitude in determining who can enter, and I could see a situation where an already angry agent saw the Vance thing, got even angrier and said you’re outta here.
The situation could certainly have been escalated by a single officer in a bad mood but there must have been some flag that caused him to be pulled aside in the first place. That doesn't mean there was any real wrong doing on the part of the guy but with many of other similar claims against the US border agents mistreating EU citizens you do see some reason why they might have been spooked if you dig a little deeper. E.g. anything that could give CBP the idea that you intend to seek work in the US is just asking for trouble.
Sure, maybe. But there’s clearly an entire other side of the story along with the Norwegian government warning other travelers, they must have their documents on them.
Don't make excuses for this abuse. The administration now in power in the US has been very clear - they oppose free speech and do not respect the constitution or Bill of Rights.