It's not about where the player was born. The other players cannot possibly know that. In JP in-game conversations people don't say "Serilda is doing something annoying", they say "that Elezen/WHM/person using the EN client in the party list" - whatever singles me out so that everyone can quickly identify the troublemaker, and the last of those is most expediently explained by using "foreigner". In this case the player wasn't communicating properly with the group, so singling them out by their language options made sense. Is it ideal? No, not really, but the spiral of disrespect began when a non-JP speaker used DF as a learning party and refused to read anything in the chat log while wasting seven other players' time. Getting angry over people getting angry is masking the actual problem here. JP players are people and their cultural expectations should be respected; it's not ok to treat them like NPCs and then rage out on the forums when one of them gets annoyed about it.