Maybe they want that the #kr tag is used only for korean language. Like #fr is for posts in french. The #france tag is used for posts about the country. You could use the #Korea tag.
I agree that english posts about Korea in the #kr tag is not spam. But it seems that the korean steemit community dont want that.
Maybe they just have no life and need something to do. The kr tag is not just for them and they use English tags too and i'm sure they wouldn't like it if they were flagged for that.