“...he urged students to do their own research and challenge him if they disagreed.”
I’m sure he anyone who disagreed with him an A+ for showing independent thought and research.
You need a high GPA to get into a good university, and challenging a liberal teacher on something as sacred to them as "white privilege" is a fast track to community college.
Let him go teach in some crappy inner city school, where he can pay penance for his white sin.