I don’t disagree. However, the principal objection to racism is not discrimination, but rather that on the basis of immutable characteristics. No one chooses their biological skin colour. So we reject discrimination on that basis.
Age gaps are not an immutable characteristic. Nor are they culturally common in the USA. So they are fair game for discrimination just like any other exercise of free association.
Age gaps are not an immutable characteristic. Nor are they culturally common in the USA. So they are fair game for discrimination just like any other exercise of free association.