Completely unprofessional and unacceptable.
My D experienced something like this–a teacher said something inappropriate during an AP biology class. I wrote an email to the teacher, but didn’t send it right away, waiting to see what happened the next day in class. D feared retaliation from the teacher/grades, as she was a homeschooler/part-time student and the teacher had questioned her placement in the class. It was only a couple weeks into the school year. My D wanted the credit, did not want to drop the class, but didn’t want to risk going through the year with the teacher (potentially) holding a grudge against her.
The teacher said the same thing again the next day. Fortunately another student called her on it at that moment in front of the class. The teacher apologized. I was thankful that student had more courage than my D. (All the students thought the teacher was out of line, but were afraid to challenge the teacher.) Another time my (then middle school) son was treated inappropriately by a gym teacher (he was injured in class, and the teacher wouldn’t let him go inside to the nurse–instead made him stand in front of the class bleeding “as an example of what NOT to do.”) I wanted to report that teacher, but didn’t because I knew that my son (non-athlete) had to get through the rest of the year with that teacher. (My son was not seriously injured, otherwise I certainly would’ve reported it.)
Some schools have a way to report bullying anonymously. I know this is usually used for students bullying other students, but maybe this behavior could be reported that way?