That’s not anywhere near the realm of “normal” for social behavior in South Korea. Buddies do more crotchgrabs and stuff here, I’ve seen that. Not total strangers. Now, the 3(?) cases I’ve experienced in 18 years here is not a lot, but… it’s enough that I can envision a handsy, 개저씨 diplomat just being transferred around when it becomes a problem, instead of acknowledging it and firing him. That’s exactly how things often get handled.