You don’t have to ban them, just deny scholorships and state funding for the majors.
Tell the critics to get a job.
You’d also have to deny employment (and tenure) for those who can’t produce rigorous study and works.
Recall, for example, the Women’s Study departments who all cited each other and gave each other awards without actual academic merit. A couple of decades ago, there was a study which showed some huge majority of studies in the field were derivative and cross-citations of merely three women doing just that.
For a long time, the only job prospects of majors in women’s and ethnic studies were in women’s studies and ethnic studies departments because in addition to being maladjusted, they’d never actually been taught anything useful.
We have to get rid of that collecting pool.