With the unipolar world of the last thirty years coming to a messy end, that's a lesson we're going to have internalize again. Be humble, be careful with the risks you take abroad, and steer clear of overtly dangerous places.
I remember seeing hotel staff act in an overtly and disgustingly racist way in Cape Town, South Africa. As a tourist, hotel guest, American, and white person, I knew that I had all of the systemic privilege on my side. So I had no problem assisting the underprivileged people in that situation.
Now, with a powerful totalitarian system like China, it might be a different calculation.
Also, it is not too hard to imagine a foreigner's "disruptive behavior" backfiring in terms of the impact on the locals' attitude towards the policy in question. Knowing whether or not your disruptive behavior will be a useful prod to change, or provoke a backlash against foreign meddling that actually reinforces the system in question, takes a lot of nuanced knowledge of the local society, which a foreigner will usually not have.
That advice wouldn't have helped the americans in the article.
But most Americans don't fuck with DPRK even if for some reason they decide to travel there. The core of the problem is they underestimate how "totalitarian" China is.