I think beating someone into submission with harsh words doesn't do anything positive. By the way, even though she didn't mean it, I personally feel safer with an elderly man than with a younger man. If that makes me ageist then so be it. I base it on experience, if that counts for anything.
I usually stay out of heated debates on this forum because I really enjoy this site. I just don't think it has to turn quite so negative. There's a way to say things and express yourself without hurting someone's feelings or accusing them of being racist/ageist, etc.
Having preconceived notions about what a class will be like isn't particularly wrong. When I go to a Jewish deli, I expect the owner or manager or someone there to be Jewish. If that makes me racist, I guess I'm racist (although I'm Jewish, so maybe not). If the deli is great, I'd still go, but if it's not, I wouldn't and maybe I would wonder if it's because the people there don't know enough about Jewish food.
If I go to a nutritionist, I expect them to be within a healthy weight range. If they're not, I wouldn't stop going to them if they had good advice, but I would just be surprised.
I don't think it's far fetched for OP to expect a Chinese instructor just like when I go to an Acupuncturist, it's what I expect...a Chinese person. If they're not Chinese, I'm just a bit surprised.
OP's overall judgment seemed more based on teaching style and she did mention other attributes of the instructor. Was there judgement there? Probably. But anyone who says they don't judge is either a saint, is unaware they're doing it or is just in denial.
Had the class been awesome, I think she would have been delighted.
I mean all this with sincerity and good intentions, but I'm ready to get slammed.