Are you not advocating "Groupthink" yourself here ?
Take China for example. So far as I am aware politics is banned in schools there. There is no politics at all, not in the western sense. Would you not call that groupthink. As in, someone says " lets talk about democracy", and the unanimous reply is, " no, that is banned".
Or Trumpism as another example. Where he wants "patriotism" taught. Or religious schools, where subjects are taught with whatever slant of that religion.
In your model, a pupil might ask during a geography lesson, " Miss, can we talk about the war there?". And if the teacher replies " No, we are banned from discussing that", then would that not be groupthink ?
If groupthink is about people in a group being under pressure to conform to the group, then surely banning certain discussion subjects is state sanctioned groupthink ? As in enforced conformity.