Teachers should absolutely be required to teach all children and to do so with equal respect— just as nurses and firefighters and other essential professionals should treat all people- especially children- with courtesy and care. This situation sounds like the teacher was not behaving professionally or with respect. For those reasons, and possibly some of which I do not know, she should be fired. However, not for her speech, no matter how abhorrent it was. The best thing about the US is our right to free speech ( even when we expose ourselves as despicable fools).