Summary: Don't confess to a federal crime when being interrogated by border patrol and expect zero consequences. This applies to all nations.
The only limitation is, given I'm French and we've just had our "9/11"-type terrorist attacks, I'm afraid we might progressively set up the same extreme police system. If we do so, I'd like to apologize in advance in the name of the people of my country...
Major international border crossings just suck a lot.
Obviously it goes without saying that its a real shame things could escalate that quickly and I'm not saying the border patrols shouldn't be ashamed.
One can certainly come away from this story with a reasonably justified degree of suspicion towards border security. But the most obvious lesson is that belligerence towards officers is almost certain to make a situation worse.
As a prospective visitor to your country it doesn't matter which official designation "they" have. It only matters what the outcome will be for me.
Whether the extraordinary reduction and enhanced interrogation is done by one arm or another of your government is irrelevant. That it happens is all that matters.
Keep in mind that the European Court of Human Rights in Strasbourg has condemned France over their use of torture in pursuing marijuana convictions. France will also somewhat arbitrarily define cases as "drug use" vs "trafficking" since possession for use is ill-defined. Many consumers get tried under trafficking laws because they get caught purchasing, for example, and under trafficking laws they will get much more serious penalties including being banned from the country in many cases. Don't forget you can also be detained for four days without a lawyer while they investigate.
Some more info at http://www.drugtext.org/European-Drug-Laws/chapter-4-france-... if you're interested.
France has a lot of great things going for it so I try not to let bad laws, border agents, etc. spoil my time there.
As he's French he broadly has no choice but to live within the laws of his state - he can campaign against them but for as long as he's there he's under them, and moving to another jurisdiction is not that easy. Whereas, he chooses to go to the USA and fall under their border controls - he's making the statement that he won't choose to do so.
While he's likely to be unnoticed by his existing state, border controls have a much higher chance of capturing interest and the outcomes are uncertain (at least in part because you're not a citizen and the way of working will feel 'foreign')
While it does sound a bit extreme, I can personally say I don't like visiting the USA any more because of the border controls. I'd probably try ad put business in Canada because of the extreme way in which the USA now treats foreigners. It can be very uncomfortable, difficult and aloof. Unless you've actually come under the purview of the TSA as a 'foreigner' it's hard to have a sense of how poorly they treat people and the general arbitrary nature of control [0].
[0] That is not to say that other countries are much better. As a UK citizen I'm pretty clear that we treat external people coming in completely differently to our citizens - and having been involved in visa applications for employees have found some of the ways in which "my government" treated people totally embarrassing.
Liars can be exposed; I don't know how to teach common sense.
I hope one day it's not like this , but treating authority like they are your buddies having a casual chat is unwise on many levels, and not just in the U.S.