Yes, that statement by itself is a bit extreme, however I believe the person on twitter was combining it with the other aspects. I did find that, at least for

Yes, that statement by itself is a bit extreme, however I believe the person on twitter was combining it with the other aspects. I did find that, at least for South Koreans, they sometimes use "Okay" in a way that would be considered non-standard by Westerners (I have no experience with North Koreans). Often times they would use "okay" more as a check or confirmation that something was heard, than an agreement. So someone saying "okay" to you could mean that they acknowledge that they heard you, rather than them agreeing with your statement. Thus, it seems like the Twitter poster was pointing out that non-standard usage and correlating it with his Korean experience.