I think you should go down to the school and make it very clear to the teacher that her job is to teach and not conduct political indoctrination.
And make no mistake at all, that is exactly what it was.
Not to the teacher, who sounds like one of those women who was fainting in ecstasy at Obama rallies, no point talking to her which will just be an argument. Go right over the teacher’s head and talk to the Principal. The teacher needs to be corrected by the principal so other students, especially those less savvy than your boy, won’t be subjected to this confusion and badgering. Of course the principal is also probably an NEA-brainwashed leftist Obama worshipper, but at least he/she will HEAR from a parent that this is not considered acceptable behavior, and perhaps realize he better keep this in check in his classrooms.