Without trying to tackle huge minority issues, I think this quote sums it up well. I think speaking with the teacher is REQUIRED in this case. She/he has to be aware of the direct insensitivity of the comments. While it may not change old, ingrained and incorrect thinking, it will make the teacher aware of how his/her comments could hurt a young student. My guess is that "it never occured" to the teacher that the remarks were insensitive.
I have watched Giselle with a corp of Wilis that was as diverse as we are here in south Florida (twice actually, with two different companies), and remembered thinking is was actually an advantage to be able to pick our a certain dancer and follow her movements across the stage and not have her become lost in a "cloud" of Willis. I know this goes against the idea that they are all to be alike, but I didn't think twice about it, probably because the cast included members of asian descent, hispanic/spanish descent, african descent etc.