When one invades the country, they of course won't feel safety (like in Iraq), but when they dont invade country, of course it feels safe, because no one is bombing and shooting locals
NK is politically aligned with the red countries, and positioned against US. Especially after the Otto Warmbier accident, some believe that Americans/Westerners in NK are in constant danger (my opinion: O.W. did something stupid while drunk; the accusations were obviously fabricated but the incident was not unprovoked), so to those, it may seem surprising that somebody can feel safe there.
The author is British working for the British embassy, UK-NK relations are strained but not as tense as US-NK relations by a mile. They had mutual embassies though the UK NK embassy no longer has an official ambassador and the NK UK embassy is closed because NK still has tight entry restrictions from COVID-19. US-NK relations are tangentially related at best.
the difference however is the level of coordination required. NK is top down, while US just has a bunch of oligarchies who may or may not be directly coordinating.