You're being unnecessarily condescending and combative.
The point that the person that you're arguing in bad faith with is making is not that we jettison immigrants and ESL students. It's that you accept that they will have struggles that the students in Japan do not (because there are much fewer immigrant students). So if you compare the students who are _like_ the ones in Japan and you come out ahead, then you go, great, we don't need to adjust for those students.
It does _not_ mean that you don't adjust for the students who have unique challenges and try to bring them up.
But if you compare two different cohorts, you might incorrectly get the signal that you should also change what you're doing for the students who don't have those challenges.