Clearly, the teacher is wrong, and the school may not settle down it well..
But if i were you..
i would not complain the school and teachers in front of the child. They will really learn just to complain/ they may even believe their behaviours are acceptable/ The parents support them for whatever they do/ Teachers get paid to teach them/ They don't respect all the teachers teaching them and at the end, learning nothing inside the school.
If I were you, i won't make it as a very "big" issue, especially in front of my child. Children are not up to the stage to judge what's right or wrong, i think they should learn to bear responsibility before knowing their rights. They should listen to the teachers for whatever reasons at this stage. They cannot handle such complicated issue. Of course, have a good communication with your child is important, so he/she will tell you all the things happened in the sch.
You may really need to think about whether you should change to another school now, as you have already complained to the princpal, I am sure all the teachers inside the school will know that, your child may not be welcome, especially by that teacher. Even that teacher will not do this again, the teachers may not encourage your child to answer questions, appreciate what he has achieved, etc.
It's cruel, but true...
I think it is one of the reason why another parent did not complain. You have already done what she wants to do, the teacher get alert about this, but his child can still survive healthy inside the school.