Of course, there’s all kinds of unanswered questions: maybe the teacher wanted to object but wouldn’t get support. Maybe teachers don’t get any sensitivity training like what’s insisted on in universities. Maybe the teacher was a passive racist who saw nothing wrong. Who knows? But to me, it seems pretty obvious the school should be reacting more like, “Oh, good grief, this is not appropriate for a school event,” rather than, “Oh golly, this got discussed online, we should do something.”